Just delete the directory and clone it again.
But that doesn't work if you rewrote history in some way (I'm not sure why that's even possible). In that case your local git can get pretty messed up, some gui tools (IntelliJ) start to bug out and fail to diff properly, and it's easier to just start over.
After ten years of using git, I've more confused by it than ever. People here keep talking about mental models, but I've read a shit ton of docs on it and am still totally confused. Probably some of us just aren't smart enough lol.
To reset the current branch, you need to do two things:
$ git fetch
$ git reset --hard origin/master
That's it. I don't know if this is more difficult than re-cloning from scratch (especially if you're doing frontend and then have to reinstall node_modules and such…)
Same thing for node modules, lol. Delete the folder and try again. If that still doesn't work, delete the lock file and try again.
It's a terrible practice, I know, but it's the only thing that actually seems to work in my experience.
EDIT: Apparently origin/master points to a specific branch. origin/HEAD points to the top of the "default" remote branch, which is often, but not always, master. Or something like that. I don't know for sure.
First is that HEAD always points to the commit that you currently have checked out. So, for example, if you have the master branch checked out, HEAD will be whatever is the latest commit in master in your local copy of the repository.
Second is that to git there is no difference between the originating repository and your own. If you had your copy of the repo fully exposed, the remote machine that you cloned it from could push changes to your copy exactly the same way that you push changes to the remote machine.
That second part is important because it means that the remote machine you're pulling from also has its own HEAD pointer. When you reset your state to origin/HEAD, you're telling git to set your own HEAD to point to the same thing as the remote machine's HEAD. This is very likely to be the same asking it to reset to origin/master because HEAD is probably pointing to master on the remote machine.
The reason it's likely that HEAD=master is that in most circumstances the repo on the remote machine isn't manually being touched. When you first setup a repo there is only a single branch so that is what HEAD points to. If no one ever logs into the machine and executes a checkout command, that's what the server is going to continue to point to.
However since there's no guarantee that HEAD=master, you shouldn't rely on that and instead always use the actual branch name.
I've seen this a couple of times at $DAYJOB when someone doesn't understand how rebase works, smashes keys until it looks like they've achieved their goal, and then I have to ssh into their box and try to unravel the damage they've done, hoping that reflog has not been GC'd yet and there's something to revert to.
That's easier than trying to get git working right, lol. It feels like every git command is a PhD rabbit hole. All I know is that if I screw something in git, trying to fix it will just screw it up worse. Reset early and often and it usually works in the end. Lol, it's terrible...
Even though I understand git really well it’s quicker to just blow it away and start again rather than accidentally make it worse realising you didn’t understand it as well as you thought you did.
Fortune favours the lazy.