I accidently run a command in my Mern project that ' npm un dev' instead of 'npm run dev' and it delete some packages and i don't know how to recover these packages.
See npm uninstall:
aliases: remove, rm, r, un, unlink
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npm install should put everything back, assuming package.json wasn't modified.
The list of packages that you deleted is still contained in the package.json file. This file is located in node_modules folder. To fix your issue, just execute the command:
npm install
or the shorter equivalent:
npm i
And those packages will be restored.
More details -> https://docs.npmjs.com/cli/v8/commands/npm-install
run npm i interminal, this will install all packages which are listed in package.json