As you surely know, joined forces of the western allies liberated France in 1944 from the nazis and they wanted to give back its independence to France. As there was not much left of the former political elite of the third republic, they formed a temporary government out of the national resistance leaders and the few surviving french politicians that did not cooperate with the germans. This temporary government was lead by Charles de Gaulle, a french general who lead the resistance from great britain during the war. Its task was to create a constitution and a elected, democratic government that should reign from that point on. On the 21st of October 1946, the constitution of the 4th french republic was accepted and Vincent Auriol became the first president elected after that constitution.

As i am german myself, i am happy to tell you something about the history of my country too :D After WW2, germany was divided in 4 zones of occupation (One british, one french, one soviet-russian, on american). The exact procedure of the occupation was negotiated in Potsdam from the 17th of july till the 2nd of august. Soon after the war, the western allies and the soviet union became rivals again, which made an early unification of all of germany impossible, even though it was planned. Instead, the 3 western occupation zones began to grow together, first forming an economic union, the "Trizone". Till 1948, both in the western and in the eastern zone, political parties and local parliaments formed and federal states like bavaria or saxony were formed. The western states elected a constituent assembly, the "Parlamentarischer Rat" (literally translates as parliamentary council) which worked out the german constitution that is still in effect today, the basic law for the german federal republic(in german "Grundgesetz für die Bundesrepublik Deutschland"). It was adopted on the 23rd of may 1949 and a western german state was founded. Konrad Adenauer became the first chancellor of the republic. At the same time, in the soviet zone a peoples congress was elected to make a constitution. Because of the russian support, the german communist party, the SED, heavily influenced the constitution and blocked it from being to democratic. The eastern constitution was adopted on the 7th of October 1949 and an eastern german state was founded. The first president of the GDR was Wilhelm Pieck.

Basically yes, the previous government (3rd republic) was pretty much gone. The few left were considered traitors as they had collaborated with the nazis and were part of the Vichy government (though there are examples of a few politicians that manages to weather through all of it - François Mitterrand was a nazi sympathizer and still became president later on...).

However De Gaulle came as the liberator of France and set up a temporary government with those he trusted (and a few administrators he didn't trust but needed). From that point on De Gaulle tried to ensure other governments had no say over what happened in France. They quickly put together a new constitution which created the 4th republic.