Can't boot into Windows 8!

Hi there,
I downloaded and installed Windows 8 developer preview on my laptop a month or two ago and was dual booting between that and Windows Seven. Yesterday, I restarted my computer and found that I had a problem booting, for some reason it wouldn't open the Win8 bootloader... after a couple more reboots it worked and this time I booted to Win7. Panicking, upon seeing that two of my partitions didn't show up in Explorer, I proceeded to do a System Restore.
This started working, and then rebooted the PC. What showed up next was "bootmgr is missing , press ctrl-alt-del to reboot".
I then left it off and hoped it would have fixed itself in the morning, which unfortunately it didn't. Since this morning I have been trying to fix this problem... I have booted from Win7 system recovery console and tried everything in command line but my Win7 partition doesn't seem to be there... I just tried UltimateBootCD and can't find anything on there that'll work.
(sorry if this post is long and boring but I don't want to miss anything out).
I think, what has happened is the Win8 bootloader has stopped working for whatever reason, and won't let me choose either operating system. (By the way, all the partitions are still in tact on my HDD). I think what I then did by trying various things through the recovery console command line is mess up the MBR of my Win7 partition and make that unusable in some way (shows up as corrupt in UBCD partition manager).
.... anyone who is still reading, do you have any ideas? Really desperate as my laptop contains pretty much everything I own, and I'm going back to Uni next week.

Sorry for long post, and feel free to move this to whichever forum it belongs in

Thanks, Cameron.