Your Wizard is safely stored at Ravenwood School of Magical Arts. Even if you uninstall Wizard101 from your computer, your Wizard, all the belongings and experience earned is still safe.
When you reinstall (either on the same computer or a different one), it may look like your Wizard is still wearing his/her starter outfit, but they're not, it just takes a little time for your computer to download all images of the clothing and items that you're wearing, so don't panic! You can verify that your Wizard is still wearing their higher level clothing by looking at it in your backpack.
If you're reinstalling Wizard (either on the same computer or a different one) there may be a larger download than you're used to at the start - so patience while that updates.
