The Old English Furniture Polish/Scratch Cover comes in two formulas - one for light woods and one for dark - and they do work quite well. Another option would be to use stain markers. Minwax makes them in pretty much every color:
Minwax Wood Finish Stain Marker - Maintenance & Repair - Minwax The Minwax site also has resources that may be helpful with other information about cleaning/sprucing up your wood items.
Goof Off (not Goo Gone) is formulated to take dried paint off of pretty much any surface. I've used it with great success any number of times on hardwood floors, hardware, etc. Again, this site has more information that could be helpful.
As far as the sink, I would refer to the manufacturer's website (if you know who made it) for information. If it is a "solid surface" material like Corian, then sandpaper can be used to even things out, and there are products that can restore the shine, as well. I've used
Weiman products for granite and stainless steel, and they are minor miracle workers.
As a last resort,
Rustoleum has some amazing products. For example, I used the Countertop Coating to change my laminate countertops from mustard to gray until we did the kitchen remodel. It held up really well for nearly four years.
I guess that the short answer is that pretty much anything is "fixable", but the long answer is that there is a lot of elbow grease in your future. My heart (and thoughts and prayers) go out to you in what is surely a very difficult (not to mention scary) phase of your life. Just keep in mind that it IS just a phase, and things will come to rights again. Keep us posted!