First of all, we are sorry to hear that. So far, there is no password restoration mechanism in place, so we strongly recommend that users remember or write down passwords and keep them in a safe space.
The only way to get access to BitTorrent Speed again is to install it from scratch. This is going to be a new wallet, so all the assets will be reset to their initial state. If you want to take this path, please uninstall BitTorrent, then get to %AppData% → Roaming → uTorrent and delete all files that are left. Then, do the same with the helper folder.