Black screen at startup

[Martin Hopkinson]

how do i get my computer to always use the last know good settings for boot
up. I have done something (not sure what) to the system, and during startup,
it just gets to a black screen and stays there. however, if i use the last
known good settings, the system starts fine. Is there a way where i can make
these settings the ones which are used each time i boot up. I have thought
about using system restore, but wondered if there was another way.

Thanks

Martin