So I have a mac computer that uses a wireless network with a password. Now I have a windows computer with a wireless network (same one) with a password. I use the same password and a pop up says that needs to use WEP or whatever password with 5 letters or 13 letters,
I try to remove the password completely from the IP entering, only to find that I cant enter the router site at all because it wont connect no matter if I use the ip for the router.
What should I do? This wireless network is a WEP 2 personal something.

the best thing i suggest is you to reset the router and config from the scratch.

config your modem and WEP password again.
It should be fine after all.

1) Unplug your router
2) Wait 2-3 minutes
3) Replug in router
4) Access internet.

Alternatively,
1) Press and hold small button on back of router for 30 seconds
2) Wait 2-3 minutes
3) Access internet.

Use the manual for reset the password.
if still u have problem then go to service center.

u can refer the user manual or call an engineer he will set your password.