I moved into a condo two days ago, and found that while the rest of the plumbing in the house has hot water, the shower when turned to hot just has a cool trickle emanating from the tap. The cold water there works just fine (in fact very well, it's downright freezing). As I'm told that it's a condo unit issue (and hence the building won't fix it) and my landlord hasn't answered his phone in the last two days, is there anything that I can attempt to rectify this issue and not freeze myself every morning having a shower?
Sounds like there is something wrong with the plumbing in the shower wall or more than likely the shower valve or stem system. If you are renting this isn't your responsibility. Not sure of your state's laws but if there is an issue like this in most states you can give the owner 2 notices and a reasonable amount of time and they have to pay for your plumber.
Again if you are renting I would not fix this yourself no matter your confidence level. Because mitigating damages will be on you.
Put something in writing to the owner. Tell them it is the second form of contact. Give them a date a few days out and say if it isn't fixed by that date you will hire a plumber to fix it.
check shower head by removing it with a wrench first. turn on water and check for flow. if still no luck, turn off water for home and check shower valve by removing either the stem or maybe a cartridge if it's a single handle shower valve :)
remember if you have hot water issue through the whole condo, then you need to check on the hot water heater and see if it's in good shape or not!