I know that the Vandals occupied North Africa for a while after the Western Roman Empire collapsed,yet i know no,at least extinct like African Romance, African Germanic,so what happened?Is it because the arabs have been there so long it's been wiped out?
'Vandalic' language is itself barely attested for, with a very limited corpus : some fragmentary sentences and one paragraph, bundled with onomastics from either late ancient authors or epigrams found in North Africa (with the caveat Germanic epigraphy in Africa include 'Suevic' generally associated to Old High German)
It seems to be firmly Eastern Germanic, but not really discernable from Gothic, except a preservation of the Proto-Germanic nominative singular *-z (rended as -s or -x) that was dropped out elsewhere, and some differences being attributable to either a stronger latin influence in pronounciation due to relative isolation or latin transcription of the language.
It's not like African Romance (or, quite likely, African Romance varieties) is well attested either : we have access to some 'Africanisms' in vocabulary, implication from African Latin to possible evolution in African Romance, etc. But we don't have lengthy texts we could compare to contemporary Vulgar Latin of Spain, Gaul or Italy to determine how much Germanic adstrate would have been important, which even comparatively to the Gothic adstrate in Spanish (to say nothing of the Frankish influence on the making of Old French) might have been significantly limited.
By the time Vandals reached Africa, they carried in their wake a variety of peoples, both Barbarians and Romans : the ten of thousands people that crossed the Straight of Gibraltar were almost certainly not just made out of the Vandals that crossed the Rhine twenty years before.Even back then, they did not formed an homogenous people but two ensembles known as Hasdingi and Silingi respectively mainly associated with Alans and Suevi, but also fragments of other peoples : according St. Jerome, Gepids, Herulians, Sarmatians as well as 'Pannonians', that is Roman provincials. Barbarians, that already were set in the broader Roman cultural sphere trough various interactions (military service, trade, raids and enslavements, etc.) became fairly romanized in the Vth century by integrating (while violently) late imperial frameworks, already settled Barbarians in the provinces they crossed and eventually the lot of Romans that joined them by opportunism (deserters, fiscal refugees, etc.) or by lack of choice (notably slaves but likely provincial coerced into service such as sailors manning ships used for piracy)
.In 429, it's quite possible a lot of Vandals that invaded Africa did not speak much 'Vandalic' to begin with, Vulgar Latin serving thus as a communication language between all these part of the Vandal entity. As they progressed eastwards and eventually established a second kingdom centered in modern Tunisia and eastern Algeria, Vandals forcibly settled in the provinces of Africa Pronconsularis and (if less importantly) Byzacena, the richer and likely the most latinized part of Africa.The opposition between Romans and Vandals there might well have been stronger than in Spain, Italy or Gaul : rather than recieving the fiscal product of the Roman demesnes of his kingdom, as it seems to have been the rule elsewhere, Genseric ordered the requisition of these demesnes in Proconsularis to directly sort to Vandals while the provincial politics were first focused on ensuring the Barbarian order in this region which is illustrated by an unique religious policy of removing Nicean clergy and a missionary effort to convert Africani workers to the Homean creed.
Whereas the collapse of the Roman state in Northern Gaul allowed Franks to gain over local elites to their own social codes (including linguistically as the Rheinish region being, besides Britain, where Latinization most obviously retracted over the Early Middle-Ages), and while the modus vivendi between Romans and Goths in Spain allowed a relatively easy collaboration and linguistic exchanges (altough especially limited in comparison to what happened with Franks), the relation between Vandals and Romans immediatly was set in a dual opposition with more obstacles to cooperation between elites and to linguistic exchanges.
This opposition was certainly not systematic nor irreconciliable : the Roman state was maintained in Africa, which required at least partial collaboration of local elites, furthermore attested such as with Florentinus being some sort of laureate poet, and kings after Genseric toyed with stopping, then resuming, the aformentioned religious policy for a probable variety of inner and outer political concerns (notably to 'normalize' relationships with the Empire that threatened twice to invade Africa) : Latin culture in the kingdom thrived, making Carthage one of the poles of post-classical Romanity, and could even be said to have done more so than after the Imperial reconquest (further irrigating Visigothic Spain intelligentia).But there was a quite exceptional political make-up and especially a more uneasy relationship with Romans at work, where compromises were harder to be made by these elites : either entierely accepting the situation and be an "household" Roman, either facing relative political marginalization while keeping one's social and cultural codes intact. That was a choice that Roman elites simply did not have to do in the other kingdoms, something aggravated, for Vandals, by the unability to oppose Mauri raiding and gradual advance to the coast and the subsequent loss of legitimacy.
Eventually, the Imperial reconquest of Africa was followed by the removal of Vandals from any positions of power, without any motivation left for provincial Romans to either adopt Barbarian social codes as it happened elsewhere : their properties taken from Roman landowners or Nicean churches were confiscated back, removal of Homean churches (where, as it happened for Gothic, the use of 'Vandalic' might have been kept liturgically),an undisclosed but probably really important number of surviving Vandals were moved to Constantinople to be forcibly enrolled in the imperial army, etc. By the VIIth century, there is no Vandals anymore to be recorded.
While the de conviviis barbaris is one of the few possible evidence for a 'Vandalic' language and might attest of its survival in Byzantine Africa, as far as we can tell in the lack of sources and influence over local Berber languages (comparatively to African Romance), Germanic influence was neglectible at best : already pretty much romanized Barbarians as they entered in Africa, maintaining an uneasy relationship with Romans and being removed from any influential position relatively early on, it's maybe not too unsurprising as a result.