My Aspire V 15 Nitro recently kept restarting by itself saying : "windows ran into a problem..."

have you read the bsod(blue screen of death)? what stop code does it give you? (like critical_process_died, etc) read the stop code and search for it online. it might also be a hard drive that is failing, specially if you have corrupted files or files that won't open or with the wrong filenames or filename extensions.