无线网卡安装完后没有信号，请问以下怎么回事

我输入iwconfig之后打印以下
enp2s0 no wireless extensions.
virbr0-nic no wireless extensions.
wlp0s20u9 unassociated Nickname:"<WIFI@REALTEK>"
Mode:Auto Frequency=2.412 GHz Access Point: Not-Associated
Sensitivity:0/0
Retry:off RTS thr:off Fragment thr:off
Power Management:off
Link Quality=0/100 Signal level=0 dBm Noise level=0 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
virbr0 no wireless extensions.
lo no wireless extensions.
我在百度上查到一些解决办法，但是貌似不太一样。求解决办法
@wzhy90 @Guanrenfu @RobinDX