My daughter is 2.5 years old. From last 2 days she is having problem in urine. Its coming in small quantity and many times a day. Pls suggest me what t?

Multiple pos causes. She could have a urine infection or may have a local skin infection. In either case, her doctor can find our the cause and help. It's important to treat urine infections early or they can spread to the kidney. Frequent urine infections may require different tests to look for other problems, some of them having serious consequences if not treated early.
Have her checked. Two common causes would be: lower tract UTI such as bladder infection; nonspecific vulvovagitis from irritation & inflammation.
Needs to be checked. Probably the most likely problem would be a bladder/urine infection. Often children cry because it hurts to urinate with an infection. If that's what it is, it is easily treated. Diabetes can cause thirst and increased urine, but in that age child, diabetes would be unlikely. That also isn't likely to start suddenly. Talk to your doctor about it as soon as you can.
See your doctor. Could be a variety of things, but she needs a physical exam and a urinalysis to better determine the cause and treatment. Could vary from urinary infection to constipation. Good luck.