Video will not play in timeline but audio will

[BUMC_comms]

Been working in this project for weeks, today when I play the timeline I can hear the audio but no video plays in the progam monitor.  in the timeline I can see the video thumbnails.  Things I have already tried are: 1. cleared all cache 2. updated my nvidia graphics driver. 3. restarted computer mulitple times

[BUMC_comms]

Update: I just turned off GPU acceleration (CUDA) and the video shows up now but I can't edit very well like this.  Like I said I updated my graphics driver BECAUSE of this issue not before this issue so not sure what to do next??

[BUMC_comms]

Update 2: I opened a completely diff project and premiere was working fine with CUDA enabled.  So went back to original project and enabled CUDA and the video was showing but after scrubbing for a second it went out again. 

[Peru Bob]

Try resetting the preferences:
https://community.adobe.com/t5/premiere-pro/faq-how-to-reset-trash-preferences-in-premiere-pro/td-p/...

If that doesn't work, try resetting the Workspaces:
Reset a workspace
Reset the current workspace to return to its original, saved layout of panels.
1. Do one of the following:
• Click the Workspace menu icon and select Reset to Saved Layout.
• Choose Window > Workspace > Reset to Saved Layout.
from here:
https://helpx.adobe.com/premiere-pro/using/workspaces.html

If that doesn't work, try Preferences > Audio Hardware and set Input to None.

If that doesn't work, try creating a new project and import the old one into it.

[BUMC_comms]

Peru thanks for the suggestions, I tried everyone of them but none worked.  Really thought you were onto something with the importing into new project - I remember doing that a few times a few versions ago.

[BUMC_comms]

Update: so this project I'm working with has like 30 sequences - it was a conference with 17 speakers. Anywho I just realized that only one of the sequences is causing this problem.  If I close this sequence, save the project, reopen file - all the other sequences work fine. If I reopen that one sequence the program monitor goes black and no other sequences work. This is some vodu level funk. 

[Christian.Z]

I think clearing preview files in addition to the cache files should solve the issue

[BUMC_comms · Accepted solution]

Ok here's what worked! every clip that was causing my program monitor to go black I deleted the applied lumetri color effect, saved the file and reopend and voila - all the clips play now.  I didn't do anything special in lumetri some just had a simple basic correction applied but when I removed it they came back.  I then reapplied lumetri color and they are still showing so this was a funky bug or something.