System repair. hi my name is Tareq, im having some problems with my computer, when i switch it on

Question

hi my name is Tareq, im having some problems with my computer, when i switch it on it brings up a black screen and it says: "windows could not start beacuse the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM. it also says you could attempt to repair this file by starting windows setupusing the original setup CD-ROM. select 'r' at rhe first screen to start repair. now i bought my computer from a friend which didnt give me the CD's. what can i do please.