My own proifle page shows Page was Not Found

Some blocks added may cause it or some new module installed..

Just in case- here's what my tech support did to fix- 

We have disabled the permalinks for your website via your administrative area > settings > advanced settings > permalinks and your profile page starts to load up normally on our end.

And it's working fine now

While that may be a solution; and you may have to live with it, I would try to find out why you can not use permalinks.

Without permalinks, you won't have the pretty http://my-site.tld/User Name

Yeah, they didn't fix your problem they just put a bandaid on it. Apache rewrite probably isn't running on your server. Is everything showing green in host tools?

Just a heads-up that rewrite_module won't show up if PHP runs under CGI or FastCGI (in Host Tools). But it should be loaded - check with your host and make sure it is. If it is, make sure the .htaccess file was uploaded. Sometimes it also needs to be edited to work with some hosts.