重装了node.js也不行，npm还是同样的问题。node.js降版本装12.18.4版本也不行，之前装的是14.12.0。请各位大哥帮帮忙，有什么解决办法。非常感谢
错误如下：
$ npm -v
internal/modules/cjs/loader.js:968
throw err;
^

Error: Cannot find module 'C:\Program Files\nodejs\node_modules\npm\bin\node_modules\npm\bin\npm-cli.js'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:965:15)
at Function.Module._load (internal/modules/cjs/loader.js:841:27)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
at internal/main/run_main_module.js:17:47 {
code: 'MODULE_NOT_FOUND',
requireStack: []
}
internal/modules/cjs/loader.js:968
throw err;
^

Error: Cannot find module 'C:\Program Files\nodejs\node_modules\npm\bin\node_modules\npm\bin\npm-cli.js'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:965:15)
at Function.Module._load (internal/modules/cjs/loader.js:841:27)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
at internal/main/run_main_module.js:17:47 {
code: 'MODULE_NOT_FOUND',
requireStack: []
}