Proceed with the steps including the hardware tests in the beginning note of Troubleshooting Windows 7 Failure to Start
to confirm the hardware first.
You said you couldn't boot but now are working from the desktop. If so work through these Troubleshooting Steps for Windows 7
Both WD Data Lifeguard and Seagate Seatools HD tests as well as memtest RAM test are on Hiren’s BootCD 15.1
which ISO can be burned to CD using Windows Image Burner or written to flash stick using Universal USB Installer
with Hirens in the dropdown menu.
If all of the steps fail then copy out your files and run Factory Recovery or get the superior Clean Reinstall.