lost files from sd card

Please can anyone advise me what are the correct files that are in the great britain file on my tomtom go sd card.
I was deleting poi info and seem to have deleted a map file as I cannot get a map to load.
there are still great britain files on the card but I dont know what I have lost.
all help greatfully received
Alistair

[Stevie]

all the original files are on the CD that came with your GO, connect to your go to your PC and then insert the CD, follow the on screen instructions to reinstall the map data