Hi boy_902,
Roblox might work better if you have access to Windows 10 or above, but if you don’t I would recommend trying to uninstall then reinstall your client. You can do this by going into control panel > programs and features and then scroll down until you find Roblox player, click uninstall and wait for it to work, then re-download the Roblox player from their official website.
Is it possible you could give me more information? Is your Roblox client starting up or does it crash when you run a game etc. ?
- Christian
(Please note that I am a community member and I do not work for Microsoft in any way. Just your local computer nerd.)