The temperature went down to 7 degrees in Phila this past Tuesday 1/7/14. I took a shower at 1 am Tuesday morning and at 6:30am I had no water in the bathroom or at the basment tub. However, I have cold water, which comes on full blast in the basement bathroom and I can flush the toilet. Are my pipes frozen.

Also, this may be irrlevent, but on the Saturday 1/4/14 prior to the freeze, I had servpro out to remove a wall, cabinets and my kitchen sink to treat for mold. Would they need to turn off the water to remove the sink? I've called them to find out and have not heard back from them yet.

Would they need to turn off the water to remove the sink?
Not normally. Normally there are shut off valves underneath the sink that affect only the sink faucet. Had they turned off any hot water valve that affected the bath, you would have known it before the cold weather.

Indications are that your hot water pipes are frozen. Should be thawing soon.