The first thing to do if the cable stops working is to check that you have paid your cable bill. Next, check the power and connections for all of the connected devices in the house. Make sure the fuse hasn't blown, the outlets are working and the devices are plugged in. Reset the devices, and determine which of them aren't working. Finally, call the cable provider.
If your provider can't come and fix the problem right away, you can try to fix the problem yourself. To fix a problem with Scientific Atlanta hardware, make sure the cable antenna wire of the cable box is connected to the Cable In or RF In on the box itself and that it is connected to a working outlet. Connect a TV directly to the outlet. If the signal is weak, remove the in-line surge protectors on the wire.
Another way to determine the problem is to check the diagnostic screen on the Motorola or Scientific Atlanta box. For Scientific Atlanta, press and hold Select on the box until the mail icon starts flashing, and press Info and Guide at the same time. For Motorola, turn off the box by pressing Power on the remote, and then press Select.
If this process doesn't work, reboot the cable box again, as doing so usually solves most problems.