It sounds like all the channel banks you have programmed are turned off. Do you know which banks you have programmed? You have 10 banks each with 30 channels. So, if you programmed frequencies into the first 3 banks...1, 2 and 3...those banks need to be turned on. Try this. Press scan and see if the bank numbers you have programmed are showing at the top of the display. If they are not, press the corresponding number on the keypad while scanning and they will activated. See the bottom of page 39 of the manual found here. http://www.uniden.com/content/ebiz/u.../BC75XLTom.pdf
It is also possible that you somehow locked out all of the channels you have programmed. You can unlocked them all by doing this...while the scanner is scanning, press Hold. Now press and hold in the L/O button until the scanner beeps twice and displays CLEAR. Hit the E button to unlock all.
I do see in the manual that All Lock Out does display when you initially turn the scanner on. Are you SURE that you programmed the scanner correctly? To see if you did, do this. While the scanner is scanning, press Hold to stop it. Now press the 1 button on the keypad and then Hold again to take you to channel 1. This should have been the first channel you programmed. Is there a frequency? Now, step through your channels using the scroll knob on the top to double check each channel that you programmed for the frequency and that it is unlocked.