Cannot find the specified in jupyter, as well as a kernel error, indicates that there is a problem with python3.
Solution:
1. Open the cmd command line window (use the shortcut key windows+R).
2, in which the jupyter kernelspec listinput: .
According to the address displayed by python3, find the kernel.json file and open it. The kernel.json file contains some information about Jupyter's kernel python3.
3, when I find the time to file directory does not exist AppData folder, indicating this folder to hide the. At this point we should:
find the search -> hidden item, at this time you can find the file.
4. Open the kernel.json file: the
red line is the address where python should exist, but the kernel error indicates that the address is wrong, we should find the address where the current python compiler is located, and then change this address to the current address, and you're done . 
5. At this time, find the anaconda folder and find the python.exe file. Copy the address, paste it in the location, and save it. (Note that the folder separator "/" in the address must be tilted to the right, "\" is wrong)
6. Close Jupyter and reopen it, as shown in the figure, Trusted.
Summary: The reason for this kind of problem is that because Anaconda has been uninstalled and downloaded too many times, there may be residual files, which makes non-executable files occupy the position of executable files, and finally cannot use python as the kernel in jupyter.
I hope I can help you.