I've seen a few threads on this and there doesn't seem to be a conclusion reached as to what causes it

I don't even know why it happened.i opened it one day and it just wouldn't download.it constantly displays "downloading"and alternates between that and "searching DHT"it's been like that for months

I've tried reverting to older versions,system restore to a point before i first installed Tixatio,nothing addresses this issue,which is a shame because Tixati is the torrent client i would prefer to use.just to rule it out i am not being throttled by my ISP and they are not blocking my torrent traffice.however this issue occurs,it's all because of Tixati


Has anybody had any success in fixing this?

I suggest you download the portable version and start with it. It'll not carry over any of the old settings and will be a ground for cleanroom testing.
Grab a torrent download for Ubuntu or Debian to test: https://cdimage.debian.org/debian-cd/current/amd64/bt-cd/  - they must work flawlessly.

With that set and if that doesn't work, you may safely suspect your firewall, network, ISP, OS etc.