Trouble with Permalinks Page Not Found Errors

Months ago I had problems with my blog that are now ironed out except for my permalinks. I can only use the default choice, which doesn’t personalize them at all. I am a complete moron when it comes to code and such, so could someone give me things to try in basic English?

I’ve tried various plugins and nothing works except the default option on Permalinks.

Thanks in advance!
Susie