It will be difficult for people on the forum to understand much from this statement. Can you describe the situation with more details and provide a screen image? What does it mean that "Thunderbird has taken over"? What do you mean by "desktop"? Your desktop computer? The "desktop" on your screen? What exactly can you not access? How have you tried to access it? Is Thunderbird working properly?

When I try to access my emails Thunderbird takes over with a completely different way of doing things which limits what I can do. Also, I am unable to access Google. My desktop computer and server are quite old so I may have to replace them.

I can only repeat my request. Please post a screenshot of this completely different way of doing things or provide more details about what you want and what is different from what you want.

What does it mean that you cannot access Google? To do Web searches? Or do you mean your gmail account? To receive messages? To send messages? Have you been able to do these things before on this computer?