when i reboot my computer, i didn't exit from ktorrent. and when i start it again, ktorrent forgot all of the down/uploads.how can i do it back?that's very important for me because i have a lot of downloads a lot of Gb and these was on 90%.

- Check whether your have not filtered yourself out in the groups tab.
- Check folders ~./.kde/share/apps/ktorrent/torX and see if the torrent files are still there. If so you should be able to import them with File> Import existing download.

Also don't put the temporary files folder on something volatile like /tmp