Perhaps you deleted the wrong Previews.lrdata
You need the Previews.lrdata that is in the same folder as the catalog you are trying to open
By the way, give us the EXACT verbatim word-for-word error message you are seeing.
Thanks for the response. I no longer have the problem. I attempted to reinstall the software which also locked up my system at the point when the installer said it was going to repair the files. I then ran an older version of LR and manually choose my current catalog and was able to proceed. I am now again running LR 5.7 with my desired catalog. If the problem resurfaces I'll proved the exact error message