Perhaps you are using the old GUI? anyway redownload the GUI from https://github.com/stellitecoin/StelliteGUI/releases

then follow below instructions then it should work. seen that people had issues with this before because they had not put it in the right place or in a directory with a space also c:\wallet stellite\ for example.

Extract the GUI wallet in a directory with no spaces like c:\stellitewallet or d:\wallet.
Exclude this directory from your antivirus as it will show a miner inside stellited.exe which is correct.
This file is needed to connect to the blockchain and without it the wallet wil fail.
Mining is standard not enabled you can change that in the Cli enviroment with commando start_mining.
Don't remove any files from the downloaded wallet GUI or add any files or folders.
When you startup wallet.exe check if stellitd.exe is running in the background via taskmanager. If not first step is check is did your antivirus blocked it.
Double check again if you are using a directory without any spaces and if you started wallet.exe with Administrator rights.
Also check if the stellite wallet is allowed access to the internet in your firewall.
It's advisable not to load both the GUI and Cli version at the same time because both need access to stellited.exe