Windows 10: Switched out motherboard

I have recently switched out my motherboard and am having difficulty finding where the Windows product key is located. My computer was activated before the motherboard switch but I am unsure what email I used as most of my old email accounts I no longer have access to (deleted)

:)

 

Choice of memory and motherboard... a bit stuck...

No one who got some suggestions on this one, huh?

I've found out that the Asus M3A78-T needs to be flashed, so then that motherboard is excluded from my list. Which motherboard and memory should I then go for? Any suggestions?

 

Airplane mode switch not working

Since the troubleshooting steps that were provided did not resolve the issue, we suggest switching on the Radio Management Service. To do that, please follow the steps below:

• Press Windows key + R.
• Type services.msc, then hit Enter.
• Search for Radio Management Service.
  
• Right-click, then choose Start.

Note: Never ever set this service to "Disabled".

Get back to us if the steps won't work.

 

PC starts only with PSU switch, beeps and turns off

I should know what's up by tomorrow evening. Thanks for all of your input.

I'm one who tries to think of step 2 before step 1 is finished. If this doesnt work I may be looking at finding a cpu/motherboard combo that I can afford that has at least the same performance as what I have, which was new in 2011. I will be upgrading eventually in the next year anyway. Any suggestions of a CPU/MB for around $300? Or less?