my computer is laggy so i am formating it now to let my post this i am going to post junk as it says i have not enough detail lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll
More about :factory reset computer compaq 6720s windows ultimate
better idea download and run these programs, malwarebyte to scan for virus http://www.malwarebytes.org/, cc cleaner to clean up dump files and your registry http://www.piriform.com/ccleaner and run chkdsk on your hardrive by right clicking on it pressing properties and tools and disk check to clean up disk errors and it should help a lot
Typically, the manufacturer will have a "recovery partition" on the hard drive.
Go onto the BIOS and boot to this partition, and it will give your the opportunity to wipe the existing primary partition and re-install the OS.