Chosen Solution

i just bought a new s9 + off ebay and i wondered if replacing the glass instead of the screen would mean touch is restored or would i have to go and buy a new screen

Glass only repairs are near impossible for phones with OLED panels. You run a very high risk of breaking the OLED panel and once that happens, you’ll need to replace the screen. And a glass only repair won’t fix it anyways.

Jessie is correct. It needs a new screen. You have 30 days after purchase on Ebay that you can return the phone