My hard drive crashed and when lightroom was reinstalled, I am getting file access denied errors in develop module. Tried reimporting from my external hard drive and the previews won't show. How do I fix?
If your hard drive crashed then you have a problem with that hard drive. Until you fix that problem, IE replace the failed or failing hard drive, you will continue to have problem with not only LR but more than likely all the software install on your computer.
In addition, reimporting is a bad idea most of the times.
As JSM already said, it's important to fix your drive issues first before trying to get LR back in order.