Did you re-download your drivers?
https://pcsupport.lenovo.com/us/en/products/laptops-and-netbooks/thinkpad-x-series-laptops/thinkpad-x220/downloads
One of these should work:
[https://download.lenovo.com/pccbbs/mobiles/gjwae3ww.exe|Lenovo Mobile Broadband Activation]
[https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/83wo14ww.exe|Ericsson F5521gw/F3607gw Wireless WAN Driver]
[https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/8awt16ww.exe|Sierra Wireless MC8355 - Gobi 3000 Software]
[https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/83wr05ww.exe|Ericsson F5521gw Wireless WAN Firmware]
[https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/7zww01ww.exe|HUAWEI EM660 Wireless WAN Driver]