Can't access C:

Hello,

I recently wanted to add some space to my computer, and found a place in settings that would turn my computer back to start (FUll reset), while in this process I got a question "Do you want to delete.. "ACER blablabla"? A list full with ACER programs. I thought YES, finnaly I can play some games. After doing all this I cannot access C: Drive, not to reinstall Windows or any ACER help program. After some "googling" i read that I might have gotten a Trojan. Please, is there anything, anyone can tell me about fixing this. I dont have CD-ROM and cannot make an USB Flash drive