First open a terminal (dash->terminal) and type ...
ps -ef | grep 2747
This command shows processes that are currently running. Example:
ps -ef|grep 2747
rinzwind 2747 3327 0 06:51 ? 00:00:01 chromium-browser
rinzwind 6002 5950 0 14:31 pts/0 00:00:00 grep --color=auto 2747
The 1st resultline is what you are looking for. If this shows anything related to chrome you can then do ...
kill -9 2747
and try to restart chrome. The kill command kills process 2747. If that fails (ie. it the
ps command shows nothing) do a ...
This command actually removes a file so be careful when typing (so do a copy paste ;) )
and try to restart chrome.
If both fail you can also do a reboot before you try to open the browser.