SOS!!! My video does not want to render on After Effects???

Without workflow details and system info it is very difficult to tell. You may have rendered it to a format that is no longer supported. This can happen if you don't have the right drivers installed or if you customized render settings. The Media Encoder failing to open a comp can be incompatible plug-ins, incompatible AE/AME builds, incompatible GPU drivers, or a bunch of other things.

More info will help us help you.

Without exact info about your project contents, render settings and so on nobody can tell you much. The usual standard troubleshooting applies: Flush your disk caches, check file and folder permissions and storage space, check your systems graphics settings and AE's as well as AME's hardware acceleration settings, try a different format like a TIFF image sequence.

Mylenium