unresponsive touch screen of iphone mobile, any solution?

[waxpro]

I purchased a used mobile phone iphone 6s for my kid,

since the first days told me that sometime the screen touch function freezes,

tried it myself: the assistive tool, the keyboard or any other option is responding,

the only option is to press the off button, then press the home button and start again,

 

i'm not sure if this is a screen problem? or software or what else to look at?

any idea about this, please advise, thanks.

[2008bangkok]

Restore the software which is the easier and cheapest way and if still the same then its hardware so then take to the shop.

[dreytom]

Maybe the screen is already a replacement one which is defective sometimes.