Engerek01: My question is, is there a way to restore my strength or dexterity any other way? Do they go away with rest? It sucks when your strength goes down to 3. Any advice regarding this issue is welcomed.
It depends on whether it's ability damage or ability drain. Ability damage can be healed by resting, but ability drain can only be removed by the proper spell. Typically poisons and disease are the most common ability score reductions, and they deal ability damage. Just make sure to cure the disease before resting or it might get worse (a healing kit will do the job).
There's always an NPC healer in every chapter that will provide full healing free of charge, and that's your best option if you're already ability drained. If you can't reach one (or it's too inconvenient) then you're stuck using the appropriate magic spell to cure it. The ideal way to handle ability drain is to prevent it in the first place by being immune to it; an Amulet of Health is a fairly reasonably priced item that makes you immune to that annoying and crippling effect.