Welcome to the community.
Could you share more details? What happens if you import a media file and double click on it to preview it in the layers panel? What are your system specifications (CPU, GPU, RAM)? Also, what's the exact version of After Effects you're using: https://community.adobe.com/t5/after-effects-discussions/faq-how-to-find-the-exact-version-of-after-...
Let us know, we're here to help.
If I import a media file and double-click on it, the sub-layer opens but nothing appears as in the picture sent earlier.
As far as system specifications are concerned, I have:
Please find attached the After Effects version.
Hold on, reopening it now after rebooting the PC numerous times and even pulling down a few saints is working normally again.
Thanks for your attention and help.
This appears to be a known bug.. try all the basics. Clear cache, re-install, reset prefs, etc.
Edit: oh my bad, i didn't see the replies that fixed. glad you fixed though!