During the night of January 24, our water pipes froze. To make a long story short, the city came by, did something and seemed to have fixed our issue. But we later realized that we have no water coming out of the upstairs bathtub hot water faucet. When we turn on the water, there is maybe a tiny tiny bit of water that comes out but that is it. We have a shower right beside the bathtub, and there the hot water works. Same for the sink in the same bathroom. Everywhere else in the house the water works. I am wondering if anyone has any idea as to why this would happen?

It is possible that just one pipe remains frozen. Since you get a dribble from this hot just open it and keep and eye on it, it should thaw in less than 15 minutes, if not come back and tell us.

Unfortunately, we tried this... still no water :(... apart for the little trickle that comes out... but that is it. Any other suggestions?

If trickling hasn't helped and its only the upstairs bath hot I suspect a clogged hot inlet. A junk of debris may have broken loose and is clogging the mixing valve. I can help you open up the valve if you can tell me which brand/model you have or post a picture

Hi there, first, thank you so much for taking the time to answer me, I really appreciate it.

The brand of faucet is MOEN... here is a photo... does this give you enough info?
http://www.izzdesigns.com/images/immr.jpg

Moen posts their own tutorials on this topic. See if this helps you Installation Help / Animated Tutorials for Moen Faucet

Thank you! Checked out the tutorials... looks fairly straight forward... will try it out!

Thank you!! We finally managed to get the cartridge out and flush out the entry... and that fixed the issue! Many many thanks!

Glad we could help.