Why does N get positive charge on it in NH4+ as I know that atom has fixed proton number, there is no change? N has 7 protons in the neutral state but when H+ comes to N and accepts two lone paired electrons of N, N becomes N to N+ why?

My question is if N has 7 protons fixed and no matter what reaction happens the number of protons does not change but why N got positive charge after the H+ receives two lone paired electrons of N? How H+ ion can combine to the protons of N and produce N+? I am confused. Explain it, please.