How can I change the lens of my camera?

Hello everybody !

I dropped my smartphone and now the lens ( to be precise, the glass outside beetween the lens and the exterior) is broken.

Since this accident, there is a black point on all of my picture. So, first question, is it the lens that is broken or it something else ? I think personnally that is the glass beetween the lens and the exeterior.

Can I change it myself. If Yes how and with what ?

Thank you very much =)