php Error after toying around with Themes

[Kuzey]

Hello!

I'm running a cpg 1.6.04. All was fine until i decided to try some different themes.
Usually, if somethings went wrong, i just deleted the theme and Coppermine used one of it's standart themes instead. This time, when i was trying the Theme, i got an php error message. I tried to go back and use a standart theme as well as deleting the not working theme.
I still get the php error. Telling me that "Failed opening required 'themes/curve/theme.php'".
Where / how can i set themes back to another one? I can log in. Only access i have is FTP and the database. But can't access Admin panel.
Any help is much appreciated.
I just made my whole gallery all new, because hoster is shutting down old databases and i were not able to upload the old db dump.
However, i had to re-add 11k photos. Don't want to do this again :/

[Kuzey]

Well, were able to fix it. Just uploaded a random theme and named the folder like it was named in the error message.
Thereafter menu appeared and i was able to set design to standart theme.

[phill104]

In the docs there is a section detailing themes. In those docs it tells you how to select any known theme simply by adding a simple string to then end of your url. This is well worth knowing for situations like this

Adding ?theme=curve for example will force the theme to be set to curve. ?theme=xxx will reset your cookie