Ethernet port not working after a lightning strike? Then I suggest obtaining an inexpensive Ethernet adapter card, and installing it.
One example of an Ethernet adapter card, (Ethernet Card, Networking Card - Same/same),http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1275962&CatId=200
The above Ethernet adapter card is a PCI style of adapter card. It plugs into any available PCI expansion slot on the Pavilion a620n's motherboard.
This is an illustration and photo of the Pavilion a620n motherboard from HP Support,http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00069442&tmp_task=prodinfoCategory&lc=en&dlc=en&cc=us&site=null&lang=en&key=null&product=424215
Scrolling to the middle of the page shows first the illustration, then the photo.
In the motherboard photo the three white long expansion slots on the bottom of the motherboard, are the PCI slots.
On this page is information on how to open the computer case, and replace, or install an Ethernet Card,http://h10025.www1.hp.com/ewfrf/wc/manualCategory?lc=en&dlc=en&cc=us&lang=en&product=424215&
Click on ~ HP Pavilion PCs - Upgrading and Servicing Guide
This is a PDF file. You may have to allow up to 30 seconds to see the first page, and additional time for the file to fully download.
[Removing and Installing an Add-In Card is information on how to remove, and install an Ethernet Card. An Ethernet adapter card is an Add-In Card]
For additional questions, and/or clarification on what has been stated please post in a Comment.