A little more info would help, but I presume that they told you to delete the catalogue lock file, and I presume you mean Adobe support?
If not, see here for it's location.
In both cases it is named [Catalogue name].lrcat.lock
Delete this file and this file ONLY. Do not delete the catalogue.
If this doesn't work, come back, and provide more information, and screen shots too.
You mean Adobe, yes?