Q: airport time machine not working

Since December 2014, my Airpot Time Capsule is not working. The computer cannot find this machine.

This is surprising...since I've been using almost for a year and it stopped working.

I connected this to computer with cable..on the back of machine, lights came with cable..but still my computer cannot recognize this time machine and it cannot backup.

I remember I changed the home internet service and changed password..but I don't know how to change the password on this machine since I cannot even access this machine.