Cant access phpmyadmin after upgrading to Ubuntu 12.04

Have you tried disabling your .htaccess file (by renaming it) to test to see if it is the issue? Maybe something in it clashes with the new version of Apache.

Thanks for you reply, yeah tried that, infact if I remove the Allow [my ipaddress] line from the htaccess, it then displays an access denied message, which is the expected behaviour, but with the Allow directive in place it gives me the blank screen/Server error

What does your apache error log say? A 500 error should have some meaningful message in there.

These are the last few entries in the error log (it doesnt mean alot to me)

[Wed Oct 02 12:47:49 2013] [notice] Apache/2.2.22 (Ubuntu) PHP/5.3.10-1ubuntu3.8 with Suhosin-Patch modpython/3.3.1 Python/2.7.3 modruby/1.2.6 Ruby/1.8.7(2011-06-30) mod_perl/2.0.5 Perl/v5.14.2 configured – resuming normal operations

[Wed Oct 02 12:49:25 2013] [notice] caught SIGTERM, shutting down

[Wed Oct 02 12:49:27 2013] [error] python_init: Python version mismatch, expected '2.7.2+', found '2.7.3'.

[Wed Oct 02 12:49:27 2013] [error] python_init: Python executable found '/usr/bin/python'.

[Wed Oct 02 12:49:27 2013] [error] python_init: Python path being used '/usr/lib/python2.7/:/usr/lib/python2.7/plat-linux2:/usr/lib/python2.7/lib-tk:/usr/lib/python2.7/lib-old:/usr/lib/python2.7/lib-dynload'.

[Wed Oct 02 12:49:27 2013] [notice] mod_python: Creating 8 session mutexes based on 256 max processes and 0 max threads.

[Wed Oct 02 12:49:27 2013] [notice] modpython: using mutexdirectory /tmp

[Wed Oct 02 12:49:27 2013] [notice] Apache/2.2.22 (Ubuntu) PHP/5.3.10-1ubuntu3.8 with Suhosin-Patch modpython/3.3.1 Python/2.7.3 modruby/1.2.6 Ruby/1.8.7(2011-06-30) mod_perl/2.0.5 Perl/v5.14.2 configured – resuming normal operations