How can I fix vtech IA5877 answering machine ?

How can I fix vtech IA5877 telephone cordless with 3 handsets and answering machine? I don't have a manual. I pressed menu to change the date and time. It asked for code and when pressed change key it changed the number to one higher. I lost the capability of getting my messages for retrieval. The message in window is CL A. It should be CL and a number of calls. I left a voice message but it can't retrieve it.