Hello, 1st) I understand that it is a desktop PC, not a notebook. 2nd) if it is a desk of a desk, in the mother near the battery has a yumper with 3 legs where it says CLEAR CMOS, Other pcs, have 2 legs near the battery, There you have to short-circuit them or touch them with a screwdriver for 10 seconds, (Nothing is erased in the bios) only factory reconfigured and you can change that at any time. If it is a laptop, take out the cover where the battery goes, and some have a soldered battery and others have a plug. Remove the battery and battery and press the ignition for 10 seconds. If the battery is soldered, the cables should be short-circuited but this does not affect the battery, if you have to unplug or cut the cable that goes to the battery, do so and then reattach it. But let's go back to the desktop PC. Formatting should only be done if you are reinstalling the operating system. But before doing anything you have to check if the disk has errors because of something lost some boot file. Program to use: Hdd Regenerator that is included in HIREN'S BOOT CD 10.4, if the disk does not make errors, test the memory with Memtest 86 which is also included in the HIREN'S BOOT CD 10.4. All this to install a clean operating system. Hopefully it serves you or others. Greetings. Mr. Jorge