GPS problem. For month ago I bought GPS navigator,and it worked very excellent.I am working in

Question

For month ago I bought GPS navigator,and it worked very excellent.I am working in ambulance,and this device helped me in my work.But onthe last duty after selection adress and push buttom"GO" I recivenotice on error program.After this occurrence GPS do not showmap and main menu.And show onli MP3,MP4 program.