Ubuntu 13.04 grub2 problem

Ubuntu 13.04 grub2 problem

I've got an Acer Aspire 5733 laptop which was happily running Windows 7
and Ubuntu 13.04 on it. Today I accidentally entered the Windows recovery
mode. This leads to an "Acer Recovery Centre" screen where there are
options to restore the computer to factory default, but I selected none of
these and just exited the screen. After this as soon as I load my computer
it says error: no such partition and has a grub rescue prompt.
I read that the thing to do was use a live CD to fix this, but my laptop
won't load my live CD (and yeah, I've put the CD drive first in the boot
sequence). I haven't got access to a USB at the minute, so I can't try
that method.
I typed ls to grub rescue> prompt and it shows 5 partitions: (hd0),
(hd0,msdos1), (hd0,msdos2), (hd0,msdos3) and (hd0,msdos5).
I have no way of telling, but I'm pretty sure these weren't the partitions
used before. Also, typing:
ls / gives the message error: no such partition like it does when the
computer starts.
I really don't know what to do now. Any help you can give me would be
massively appreciated.