Need router help

How can I re-program a “dlink” router (model dir-615) to make secure?
Long story, but condensed version:
I switched internet providers, but the original never cancelled, so I decided to keep for a while so as to make sure I was going to be satisfied with # 2.
After a couple of weeks, I was satisfied and unhooked my original modem & router.
Found out later that any overage on # 2 was going to be atrocious, so re-hooked original modem & router.
Only problem, password no longer valid.
Reinstalled using CD for router and went through no telling how many “phases” that never panned out.
Somehow, sometime, it decided to connect, (????) so now I do have the system working, but I have no security on the Wi-Fi.
I actually called the “Dlink” tech support, but I have a bit of a hearing problem and after trying two females that had very definite accents AND high pitched voices (that really give my ears fits) I just gave up - especially since I was going to have to pay for this info.
May have to go back and try to get a bass talker??!! :tongue3:
Any help appreciated!!

 

'Preciate the reference.
Went here and followed several approaches noted, but ended up with the same result - working Wi-Fi but unable to secure the connection.
Ain't giving up yet though!
Thanks again as this did give me something to start from - which I needed seriously!

 

Thanks, will check this out and get back to you!
Lotsa family goins-on right now, so will be a few days.