For possible uti can I use 2 yr old bactrim?

I realize this question is probably not relevant to the original asker, however it is a common question. Using expired, leftover antibiotics is not advisable. For one thing, the dosage you may have might be sub-therapeutic - that is, there might not have enough left to do the job. If someone takes sub-therapeutic doses of antibiotic, they run the risk of not killing off all the infection. This can cause the ones that remain to mutate into having a resistance to the antibiotic. Also, antibiotics are relatively unstable as far as shelf life. It is always best to see a doctor and get a prescription that is targeted for the actual infection in the correct quantity to ensure it completely kills off the pathogens.

Self diagnosis is not a good idea. If you suspect you have a UTI see your doctor.