Unresponsive touchscreen

Hi, I'm recently facing a problem with my touchscreen's responsiveness. Whenever, I unlock and use my phone, the touch works fine. However, barely a minute in, and its starts becoming unresponsive and finally doesnt function at all. In this case, I normally lock and unlock my phone and it works fine again, only for the touchscreen to be unresponsive again. Has anyone faced such a situation and know what can be done? Please help. Thanks.