Update said missing stylesheet – then tried to update via ftp – now can't log on

HI,

I tried to do the enfold update on the wordpress side – it said it had failed as missing stylesheet. So I downloaded the files and tried to upload via ftp – but I have done something wrong big time as now I can’t even log on to the wordpress site – it is just showing a blank white page when I put in wp-admin.

Then after a while it is saying internal server error.

What have I don e- any ideas?
http://www.generatorservicing.com

Thanks!