我的python3.7 的pip3突然不能使用，也无法升级或者卸载，不能install任何第三方库，都报相同的错误

```shell

F:\python3.7.9\Scripts>pip3 -V
Traceback (most recent call last):
  File "f:\python3.7.9\lib\runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "f:\python3.7.9\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "F:\python3.7.9\Scripts\pip3.exe\__main__.py", line 4, in <module>
  File "f:\python3.7.9\lib\site-packages\pip\_internal\cli\main.py", line 10, in <module>
    from pip._internal.cli.autocompletion import autocomplete
  File "f:\python3.7.9\lib\site-packages\pip\_internal\cli\autocompletion.py", line 9, in <module>
    from pip._internal.cli.main_parser import create_main_parser
  File "f:\python3.7.9\lib\site-packages\pip\_internal\cli\main_parser.py", line 7, in <module>
    from pip._internal.cli import cmdoptions
  File "f:\python3.7.9\lib\site-packages\pip\_internal\cli\cmdoptions.py", line 25, in <module>
    from pip._internal.locations import USER_CACHE_DIR, get_src_prefix
  File "f:\python3.7.9\lib\site-packages\pip\_internal\locations\__init__.py", line 9, in <module>
    from pip._internal.models.scheme import SCHEME_KEYS, Scheme
ImportError: cannot import name 'SCHEME_KEYS' from 'pip._internal.models.scheme' (f:\python3.7.9\lib\site-packages\pip\_internal\models\scheme.py)

```