Changed R Library PATH and now R wont work

I updated R to the latest version (4.1.0) and now I am getting a few different errors that I have no idea to fix, even after searching online.

The Rtools was then not working as it said it did not run on the latest version of R.

I get the following error:

WARNING: Rtools is required to build R packages but is not currently installed. Please download and install the appropriate version of Rtools before proceeding:

In my heist to try and fix it I think i have changed my path location, and now nothing works. I get the following error when i try and install and load packages:

 LoadLibrary failure:  The network path was not found.

I also get this when i check:

[1] C:/Users/USER/Documents/R/win-library/4.1
[2] C:/Program Files/R/R-4.1.0/library


Sys.which(`make`) make

When i go into tools and check the install packages location, it has now set to my personal library ([1] C:/Users/USER/Documents/R/win-library/4.1[default]) and no option for the [2] C:/Program Files/R/R-4.1.0/library` shows up, and hence why i cant find any packages (at least i think thats the issue).

How do i go about changing the PATH location to get access to the packages again? I have tried uninstalling and reinstalling and the error still remains. I cannot install any packages or call on any packs in the library and hence cannot do any work.