Unknown DirectX Error Has Occurred and League of Legends cannot start.

My game client stopped functioning out of the blue, and the error message that pops up is:

"An unknown DirectX error has occurred and League of Legends cannot start. Please make sure your video card is using the latest video drivers from the manufacturer."

I have already tried to:

• update my graphics drivers 3 times to no avail (including the one that wipes existing)
• delete "DirectX" under microsoft/directx in "regedit"
• reinstall league twice
• repair game client
• disable Graphics card drivers and re-enable
• installing directx (dxdiag thingy built in to windows sees no issues, directx 12 installed)

What's really interesting about this whole debacle to me is that none of my other games have this issue. None of them. Just League.

Any ideas as to a solution?