no dash or menu after upgrading from ubuntu 14.10 to 15.04

When I boot I get to the login screen fine, and then after login I get a screen with my wallpaper and mouse cursor, but no menu, no dash, ctr + alt + T does nothing, clicking the mouse does nothing. I've tried to get a text prompt using ctrl + alt + F1 - F6, but they take me to a completely blank screen with no prompt, ctrl + alt + F7 takes me back to my wallpaper and cursor. All the other solutions posted need me to be in a terminal window, but I can't get into one.

I upgraded from 14.10 when this happened - the upgrade seemed to go ahead like normal. This machine originally had 10.04 on it, but has been upgraded every 6 months with no issues .... until now!

I can get into recovery mode, but don't really know what to do to fix it from there.

My machine is an ASUS laptop with a radeon HD6320 graphics and an AMD brazos E450 processor.

I have created a bootable dvd of 15.04 and that works fine!

my .xsession-errors file has some odd entries - does anyone know what they mean?

openConnection: connect: No such file or directory cannot connect to brltty at :0
upstart: upstart-event-bridge main process (1552) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1560) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1568) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1589) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1590) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1592) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1593) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1596) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1635) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1636) terminated with status 1
upstart: upstart-event-bridge main process ended, respawning
upstart: upstart-event-bridge main process (1637) terminated with status 1
upstart: upstart-event-bridge respawning too fast, stopped
upstart: update-notifier-crash (/var/crash/_sbin_upstart.119.crash) main process (1591) terminated with status 1
Xsession: X session started for benj at Fri May  1 22:06:50 BST 2015
localuser:benj being added to access control list
/etc/X11/xinit/xinitrc: 8: [: x: unexpected operator
openConnection: connect: No such file or directory
cannot connect to brltty at :0
Xsession: X session started for root at Fri May  1 22:25:26 BST 2015
localuser:root being added to access control list
openConnection: connect: No such file or directory
cannot connect to brltty at :0
/etc/X11/xinit/xinitrc: 8: [: x: unexpected operator

This is a long shot but I ran into the same issue as you and it took me an hour of trial and error to fix it. I haven't figured out why, but the unity settings are probably messed up.

You need to start the compiz config settings tool. I couldn't figure out how to start it from command line so I started up a cinnamon session where I could start the settings tool. In the settings tool I, quite frankly, messed around a bit. Checked and unchecked the OpenGL plugin and the unity plugin. I think the latter is probably what made it work, since it yelled back at me with warnings and conflicts.

After this. I logged out and logged back in again and unity was back.

I had the same problem, and all I had to do was:

sudo apt-get install unity && unity

and my desktop immediately fixed itself.