Big problem with my Pc

I have Windows 7, i used to have 32-bit version. I wanted to have 64 bit version so i installed it, but it still keept 32 bit version, so i can choose which one i can enter when pc is turning up. Both of these boots have problem: 32bit started acting wierd very soon (very laggy) and one day i just entered it and i got msg that .dll is missing; I searched help for this online most of them said to download new .dll stuff, but the even more problem is that mouse doesnt work on that boot, so i cant even fix it. Now for the 64 bit version it didnt have sound since the beginning iistalled it, i tried everything i could, but nothing worked. My pc is very old (it was solid in 2012), but i wanna have it for little bit more till i get new one. So if someone can tell me how to fix this issue ( i dont care which boot, just i want one to be fixed and other delated).That is all, thank you.