My computer won't start up anymore. What can I do?

Hi all, I have an Acer Aspire R5-471T notebook which seems very reticent to work with Ubuntu 14.04. It crashes or freezes with some frequency and on restarting drivers seem to be missing (for example, I keep losing wireless). Sometimes the computer apparently freezes but the mouse pointer remains mobile (but unable to click) anything. Reading advice online intended to fix this, and not wanting to restart and lose more drivers, I tried to fix the problem from tty1. I was able to restart gdm (I can't use lightdm anymore either for some reason) according to the terminal feedback, but it didn't appear in tty7.

Something I read online suggested the problem might have been nvidia drivers, but I suspect following this suggestion made things worse. When I eventually sudo rebooted, the normal login happened, but after the dots I found a black screen. I'm able to get to a terminal via the following workaround:

• restart in recovery mode
• resume regular boot
• accept the error "*Starting ACPI daemon initctl:
  Event failed" which occurs in tty1
• log in to terminal there.

I've tried purging nvidia and doing apt-get install nvidia-352 but I have the same problems. I see there are several versions of NVIDIA flies but don't know which are relevant. So I don't even know if this is really the problem. What can I do?