Hi @Sundip,
Are you having this problem with other models? If not, it’s possible your model might have been corrupted in some way. If you’re willing to attach the file that won’t open, our team would be curious. You can also send me a private message if you prefer.
Depending on how many revisions of your model there are, you might be able to revert to a clean version of the file. In Trimble Connect, navigate to the original file that didn’t save. Then follow my instructions in this forum post to download revisions of your file. You can try opening those in SketchUp, and I expect (hope!) that one of your most recent revisions will load successfully.
Hope this helps,
Mark