Demorthus :
If the drivers of the GPU are going to be erased do the following:
1) Unplug the power connectors to the GPU (OR take it out if you want; does the same thing)
2) Unplug your HDMI/DVI/ OR DP from the GPU to the motherboard's, that way you can get a video output.
3) Do your restore, head to NVIDIA's website afterwards, install driver, and plug everything back to the GPU- Done!
1.You dont have to remove the GPU to do a factory restore at all.
2. Leaving the GPU in without the power connectors is not the same as removing it, the GPU will just run off the PCIe power, and crash when put under any stress.
3. If OP hasnt got an onboard GPU, how is he meant to see how to install the GPU driver again?
4. The windows driver will kick in until you can reinstall the full Nvidia driver from disc / the Nvidia website.
OP, end all steam processes in task manager, and then delete clientregistry.blob from your steam directory, this holds the client info. This will make you login again when you open steam, and should fix the problem.