Have an sti two cases were detected ureaplasma parvum and gardnerella vaginalis, only symptoms im having is struggling to urinate but with no pain. what should i take so my urination goes back to normal?

Find out from the MD who ordered that culture and take the appropriate antibiotic to which they are sensitive. Drink adequate amount of water, practice safe sex. If you don't improve with the antibiotic you ought to see a Urologist

This isn't an STI problem. U. parvum and G. vaginalis are entirely normal bacteria in the genital tract. GV is associated with bacterial vaginosis in women, but no problem in males. UP never causes symptoms or disease. And no STI is a likely cause of "struggling" to urinate (e.g. slow flow, possible blockage, etc). See a doctor, ideally a urologist, to include evaluation for a prostate infection.