Why don't you have Restore Points? Do you know?
What was the infection found by WDO?
You'll need to confirm WDO has disinfected completely, try booting into Safe Mode to run Malwarebytes or another bootable AV from list. Knowing the type of infection can help our Security experts tell you what to run to combat it, as can a quick Google search which may point you to one of the bootable AV's which specialize in that infection.
Once it's confirmed clean, then run SFC from installer/Repair CD Command Line as Colin suggested. Then if necessary work through the rest of the steps which try everything possible before rescuiing your data and running HP Factory Recovery
or Clean Reinstalling.