Howdy,
First off, I don't think it was installing mcrypt that made it so you can't access the system, something else is going on :-)
Second, can you clarify what exactly isn't working? It sounds like you're saying both FTP and Virtualmin aren't responding?
Are you able to ping the box (from the windows commandline, you can type: ping YOURDOMAIN.com)?
If so, then the box itself may be online, it may just be one or more services that are unavailable.
You can try installing Putty to access the system via SSH from within Windows. Putty is available here:
http://www.chiark.greenend.org.uk/~sgtatham/putty/download.htmlAt which point, you can start the services that aren't running ("/etc/init.d/webmin start" -- for example).
If you can't ping the box though, it sounds like it may not have booted up, and you may need console access to figure out what exactly happened (it may simply be powered off -- or there might be an error displayed on the console).
-Eric