I think I have a spyware on my computer. It can't be detected by antivirus, so I can't find and delete it. How to protect Tor browser from this spyware that it doesn't get access to Tor files and Internet? In my firewall only Tor browser is allowed access to Internet, and all other outgoing connections are blocked. My OS is Windows 10 Home.
By not telling us what OS your running, you've made it hard to give you an exact answer.
The following is a semi-generic answer, that covers the 3 most common OS's to a limited degree. However it goes much further than simply protecting the TOR browser for the simple fact that without getting outside the OS, there is no guarantee the infector does not have primary OS access, meaning it can see/block any actions with the authority of the OS itself.
All of the major OS's(Windows, MacOS, and Linux) have the ability to run virtual machines.
Windows 10 pro,edu,enterprise can enable Hyper-V
VirtualBox is available for all three platforms, including Windows 10 home.
After enabling/installing the ability to run a virtual machine, you have a couple of choices:
If you wish to run Windows 10, there is a 60 day eval Windows 10 VM available from Microsoft. This image is 20GB and includes almost everything but the kitchen sink(It may even have that, but I did not download it to see).
You would make the firewall open only for the VM network interface. At this point only the programs inside the VM can access the internet. Depending on the exact VM manager your running, you would then be able to download various anti-virus/anti-malware programs to the VM and then copy them over to your primary machine.
NOTE: If your VM manager is unable to start claiming another Hypervisor is already running, then it looks like your malware/virus is rootkit with hypervisor capability. At this point you'll have to get a live run system(either USB or DVD based) installed from another machine and booted on your infected machine, to have a chance to bypass the infection.