Hello,
The only texts they consider sacred and complete are the Quran and the Sunna (contains the hadiths which are a compilation of teachings and conversations from Muhammad) which they both require as I recall from islamic studies back in high school.
Also, further to what mikeeh has mentioned in order to avoid confusion such as something like ‘does this mean that muslims previously believed in Christian teachings?’: In fact, as muslims do hold that the preceding books such as the Torah, zabur, and Injeel, were Divine revelations they would argue that these came with the prophets ( who were 'muslims) and only they held to scriptures truly and that their followers corrupted them. I have a close muslim friend at university so we’ve discussed TN this several times. She would tell me that i.e. John the Baptist and Jesus, followed the injeel, as ‘true muslims’ and that the injeel or gospel was corrupted.
So to answer your question briefly: muslims seem to ‘believe’ that held these texts once. But do they have them? Not at all, because they cant tell us what happened to them other than nonsense like they had been corrupted without even being able to discuss what it is that was initially corrupted. The only answer i recieved from my friend when I tried to ask what they were about was that God had destroyed the books which gave no fruit to the discussion but I hope you actually learnt something in regards to what muslims hold today as sacred scripture.
