Ok so if you did not read this entry before deleting the new NextGen... and got an almost heart attack when trying to figure out what happend and saw that everything was lost... then maybe the following might be of use:
I made a backup and reinstalled an old version of the NextGen Gallery through ftp and then went into my WordPress admin.
go to add gallery-images
go to Import image folder
brows in wp-content/gallery/
and hopefully you will find all your pictures there like I did.. You do have to ajust your pages... It is still a bit of work, but at least you do not have to upload over 1000 picture like I did..
now take a cup of coffee, stop shaking and try it after taking a deep breath!