Lets try to tear your question apart.
I got the trojan virus on my Dell laptop so I reinstalled Windows. Now I'm having problems getting stuff back. Hew do I reformat after I reinstall Windows?
Okay what do you mean by reformat? What did you do with your laptop? Did you format or did you reinstall it all? Best way to summarize, reinstall your files still there. Files all gone probably a restore to default settings OR a full wipe and format of your hard drive for a clean XP install with an XP disk.
And how can I get back the wireless access on my laptop? After I reinstalled, my wireless connection doesn't work..do I have to do something to get it back??
Yes... I guess you formatted then. Your laptop... go to dell look for the drivers... Sometimes you can just enter the service tag number somewhere on the bottom and it will tell you what you need to get. You probably could benefit form getting the drivers for it anyways.
Also, when you use dsl broadband, do you need to have wireless access? (sorry if it's a dumb question, I'm really not good with computers.)
In the past, did you use your internet on wireless? Its not necessary at all... you can connect to any form of internet wired or wireless. You can just connect a standard network cable to your laptop and hope it works.