Please help, really really need it!

Hi

I have a Tomtom Go 520, I have paid for and downloaded the map of s/e USA from Tomtom direct and I have it on my sd card. The tomtom wouldn't recognise it as a map so I decided that the best way to fix it would be to put the USA map direct on the tomtom. Of course the memory is too small to take both so i took off the uk map and then tried to put the USA map on. It did go on but then told me that 'no maps found'. Now I cant get anything to work and I have got myself in a complete mess. i am going to Florida early Sunday morning and really need it for then (25th may 2009). Can anyone help me to sort this mess out, i would be really grateful.

Thanks

[getsurfers]

Use the home application to temporarily remove your UK map and put the US one on.

Put things back the way they were and do a back up first!!! (assuming it works again with the UK map)