Cannot find any drives

could anyone please help me!!!
i recently experienced my computer crashing for no apparent reason, when it booted back up it seems to take ages. i am not really computer literate, so any advise would be appreciated.
when i go into my computer it says they are there but they have yellow warning signs attached to them, i was then advised to update the drivers, but the retailer i bought my system off has recently closed down and didn’t get any discs with them and it says nothing was found when i try to update.
in short, non of my writers work or even when i mount images via daemon tools it is not recognising even that drive.
PLEASE COULD SOMEONE GIVE ME SOME ADVISE!!! it is becoming very annoying.