My Blog keeps forgetting its theme

Hi I upgraded my blog from 2.0 – 2.1.1 and now it keeps forgetting its theme.

I uploaded a theme and it would keep reverting back to the Kubrick one so I deleted the Kubrick theme and now everyone few hours/days it forgets its new them and stop displaying all together (because it can’t find Kubrick I assume).

What the hell is going on? Is this not the wierdest thing ever.

If anyone has any ideas it would be really nice to hear them as this is my main site and this is a little distressing.

If you should need to you can see my site here https://www.techwinter.com

Thanks
Roger
PS. Interestingly it doesn’t forget where to position my sidebar widgets when I get my theme back up they immediately go back to where I had them before and not the default positioning

Thanks again.