Peter Heather's The Fall of the Roman Empire: a New History of Rome and the Barbarians (2005) and Adrian Goldsworthy's The Fall of the West: The Death of the Roman Superpower (2009) are two excellent books on this topic. For an introduction into the world after the 'fall', Heather's The Restoration of Rome: Barbarian Popes & Imperial Pretenders (2013) is pretty awesome, then perhaps you can try Peter Sarris' Empires of Faith (2011) and Chris Wickham's The Inheritance of Rome (2010) if you want more details. Various chapters from Volume 14 of the Cambridge Ancient History (2001) are also pretty good for shorter but more academic approaches to the period, especially if you can access it for free from a university library. For a more archaeological approach that emphasises the terribleness of the 'fall' of Rome (whereas the authors above are inclined to see it as a gradual decline rather than a great catastrophe), Bryan Ward-Perkins' The Fall of Rome and the End of Civilization (2005) is the best introduction.

For primary sources it's a bit more problematic since modern translations are rare. For an insight into the world of an average Roman, the Life of Severinus is probably your best bet, as it chronicled the struggles of Romans living in a post-Roman world - luckily they had a saint on hand to help them, but the picture it paints is still a rather depressing one. Everything else is a bit fragmentary and there aren't any easy-to-read primary sources that cover all the important bits of the 'fall', simply because it was a gradual process that took nearly a century to occur in only half of the empire. My recommendations above are all excellent at piecing together the evidence and in providing an enjoyable narrative though :)