You need to
a) change the phone jack (pretty easy)
b) find a phone cord that will pick up the appropriate line fron the jack and take them to the phone.
If you look closely at the phone cord you will see the contacts. A single line will have only 2 contacts, a 2 line phone will have 4 (the most common type)
If you replace the jack, pick a pair, hook them to the approprioate terminals.
Here, the standard colors are blue/blue,white= line 1...orange/orange,white= line 2. Old school jack colors wer red/green=1, yellow black= 2.
Plug your phone into the new jack and touch the pairs one at a time and listen for a dial tone.
I hate phone wiring.