What do I do if I'm sick with a cold and my ears won't pop when I try?

Multiple. Decongestants if not contraindicated, mucolytics, and mental valsalva maneuvers-like moving jaw or gently blowing nose/
Decongestants. Firstly don't try to pop ears when you have a cold, you will often push mucous in to them. The key to relieving ear pain with a cold is controlling the nasal stuffiness. Medications such as afrin, which can only be used for 3 days, or Pseudoephedrine can rapidly improve the congestion, and hot showers or steam can help as well. Once the congestion is better for a few days the ears will pop.