I looked it on that was well, but couldn't find it... it seems that this toll is quite complex, but I'm learning
Anyway, I manged to get help from locals here - some (hidden) administrator, who reset the Theme on the Topic format, instead the one causing problems...
Many thanks for your help, and for the topic, if someone is using the web based version only (don't know if I'm correct in expression), than, by my opinion, the only way is to contact administrators.... or at least to gain Administrator rights.