Bench reinstall problem

Hi all,
i have a problem when i try to reinstall the bench an also in install app from git, it was like that:

This will wipe your database. Are you sure you want to reinstall? [y/N]: y
Traceback (most recent call last):
File “/usr/lib/python2.7/runpy.py”, line 174, in _run_module_as_main
main”, fname, loader, pkg_name)
File “/usr/lib/python2.7/runpy.py”, line 72, in _run_code
exec code in run_globals
File “/home/frappe/frappe-bench/apps/frappe/frappe/utils/bench_helper.py”, line 79, in
main()
File “/home/frappe/frappe-bench/apps/frappe/frappe/utils/bench_helper.py”, line 16, in main
click.Group(commands=commands)(prog_name=‘bench’)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 722, in call
return self.main(*args, **kwargs)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 697, in main
rv = self.invoke(ctx)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 1066, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 1066, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 895, in invoke
return ctx.invoke(self.callback, **ctx.params)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 535, in invoke
return callback(*args, **kwargs)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/decorators.py”, line 17, in new_func
return f(get_current_context(), *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/commands/init.py”, line 24, in _func
ret = f(frappe._dict(ctx.obj), *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/commands/site.py”, line 138, in reinstall
frappe.init(site=site)
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 151, in init
setup_module_map()
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 830, in setup_module_map
for module in get_module_list(app):
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 704, in get_module_list
return get_file_items(os.path.join(os.path.dirname(get_module(app_name).file), “modules.txt”))
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 662, in get_module
return importlib.import_module(modulename)
File “/usr/lib/python2.7/importlib/init.py”, line 37, in import_module
import(name)
ImportError: No module named erpnext

how can i resolve it, i can not install any app to my system

Install ERPNext app first and then try.

bench install-app https://github.com/frappe/erpnext

i solved it
thank u @KanchanChauhan