I had two viruses stored in the virus chest. Soon after I used System Recovery to restore my computer to it’s original state.
Could the two viruses still exist on my computer.
The two viruses with the exception of the ones you sent to the chest don’t exist on your system.
System Restore isn’t a back-up tool and is fallible and may not give the results you want. It would have zero effect on the files stored in it as it is a protected area and system restore wouldn’t cover that anyway.
If any of your restore points were infected then if you use system restore and go to a point that includes an infected restore point then you could be re-infecting your system. Hopefully avast would have detected those also and you elected to move them to the chest, etc.
Why did you need to use system restore ?
So I would suggest that you rescan your system with avast, schedule a boot-time scan would be quickest and quite effective if system restore placed items back in the system folders. Or an on-demand thorough scan longest.