Acer Aspire AM110-E1304A Vista

Hello,
Suddenly, our computer went to a black screen asking for a boot disk. I foolishly didn't back up the system. I searched on the internet and found a "fix". Restart computer, hold "alt" and continuously press the F10 key. Well, it did eventually take me to the usual Window screens and I could then use all the usual programs for about 5 minutes. Then, everything stopped responding and about one minute late, I was back at the black screen asking for the boot disk. I do appreciate any help I can get. Thank you.