my avatar is invisible, and I have tried mnay things, reload. new skin, shape and remove all clothes

[Cinnamon Lohner]

Truly invisible or a particle cloud?  I'm going to go with truly invisible since you've been in SL for a while.  This wiki article looks a little dated but it may have a couple good suggestions including if you are running 2 monitors.

http://wiki.secondlife.com/wiki/Invisible_Avatar

--Cinn

[Cinnamon Lohner]

Truly invisible or a particle cloud?  I'm going to go with truly invisible since you've been in SL for a while.  This wiki article looks a little dated but it may have a couple good suggestions including if you are running 2 monitors.

http://wiki.secondlife.com/wiki/Invisible_Avatar

--Cinn

[Venus Petrov]

You have not accidentally derendered your avatar, have you? In any case, if you had, you would reappear the next time you logged on. So, if that is not what is happening, it is something else.