So last afternoon, i decided to open my pc up, right when it said: Starting windows…

it automatically switch to the start up repair thing (OS: Windows 7) and it does nothing

i checked the repair logs, it said: “Registry Corrupted" but i did fixed it thanks to some youtube tutorials, then it still switch to the startup repair even tho it clearly says: “Boot status indicated that the os booted succesfully” while it does not, i searched it on google and the only solution i found is system restore or something like that, but i dont have any of these kind so im kinda screwed

All data stored in pc are quite important and i cant lose it, i really need helps and ill really appreciated it, thanks!