Just a guess, but did you turn level 41?
The dragon lord buff on channel 1 deletes itself as soon as the player turns level 41. With deletion of the buff all benefits of it are lost (including it doubleing your hp/mp).
Staying on channel 1 after level 41 makes no sense, the buff won't return.
Could this be the case?
If so, nothing bad has happened to your hp/mp. You are just back to the normal hp/mp of your level. The original ones you have, not the buffed ones.
Edit:
Staying logged in all time when started below level 40 makes the dragon lord buff continue even over the level limit it comes with. But only till the second you log out, after logging back it is gone. (you said you stayed logged in the whole day yesterday, so this sounds familiar....)
Edited by Fliederduft78, 22 August 2015 - 10:42 PM.