it is difficult to diagnose and suggest options.
All I can suggest is 1 of 3, or may be all three;
1] System Restore to when it worked.
2] Scan this system with your anti-virus and anti-malware in the SAFE MODE option.
3] Wipe the OS and reinstall it.
My other computer has problably a virus. I cant use internet then i realized that i cannot connect the computer with the USB connection. Has anyone else got this kinda virus? plese help me. anyone know what i can do? By the way sorry for my english...