My upstairs bathtub spigot has no hot water (it has a trickle) but it does have cold water, the sink is fine as are all the others throughout the house.

We had the house built about 5 years ago, it's a guest bathroom so it's rarely used, may 3 times (if that). It worked fine the few time we did use it but then it just stopped.

Ideas?

Brand would help us. There is probably debris in the hot side orifice of the cartridge or valve body, single handle faucet presumed. You need to remove the handle and escutcheon plate, turn the water off, remove the cartridge, make sure the holes are open in the cartridge and open the hot water side to blow out the line. Reassemble and it should work. Disassembly of the faucet depends on the manufacture but most cartridges are held in with a retaining clip. There may also be an anti-scald ring too.