Format mo na lang, kung dalawa drives yan format mo yung system drive(C is very common). Tapos install mo AV(Antivirus) then update if not updated ang AV you. tHEN Scan both drives... After scanning and cleaning(virus,malware, etc), install mo na drivers mo essential programs and the like...
if isa lang drive mo... format pero iretain mo lahat... pwd yan.. Then install AV then driver, etc.