Impossible to record at normal sound level

Hi.
I hope someone can solve this problem for me. I’ve looked at many posts on here under different threads, and while there are some similar questions, no-one seems to have exactly my issue, or a solution.
I’ve been using Audacity on XP and Win7 for years. Very successfully, no problems.
Now I have been dragged kicking and screaming onto Windows 10 and I cannot get Audacity to record at a proper level. Virtually a straight line on the blue waveform and it’s so quiet I can hardly hear it. Amplifying it after recording does not help, as this also amplifies any hum/whine/hiss.

I have tried Audacity version 2.0.2 (successfully on XP and 7) and now on Win 10. Then I installed version 2.3.3. Neither version recorded correctly. And I have tried every combination of MME/Windows Direct, and Speakers RealTek Audio/Sound Mapper, and of the 4 inputs, only Sound Mapper and Jack mic produce anything at all.
However, unplugging the mic produces absolutely nothing whatsoever, so it seems Audacity is only recording from the mic, and not from any internal source at all.
I have downloaded the latest drivers for Realtek Audio and that hasn’t helped either.
I also tried to install the Realtek HD Audio Manager, thinking that might give me more control over the sound output, but although the folder appears in Program Files it won’t open or start, no matter how many .exe files I click. About three hours on the Web searching for an answer to that problem didn’t produce a solution, so I only have the basic Realtek sound system in my Dell Inspiron 3671.
Browsing this forum I did notice that other Dell users have issues too. Sound enhancements is unchecked.
I suspect that part (or all) of the problem might be that this PC doesn’t appear to have any preamp, as I have to use powered speakers, whereas the old XP and Win7 systems had speakers of their own.

Can someone please try and provide a solution to getting Audacity to record at a decent level on Windows 10 ??
Thank you.

I have tried Audacity version 2.0.2 (successfully on XP and 7)

Same computer or different hardware?

Dell Inspiron 3671

Does that computer have separate mic & headphone jacks or a single combo jack?

and of the 4 inputs, only Sound Mapper and Jack mic produce anything at all.
However, unplugging the mic produces absolutely nothing whatsoever, so it seems Audacity is only recording from the mic

So, the microphone is working? What are you trying to record from?

Sorry. Didn’t make myself clear. Previously, (XP and Win7, different computers, HP desktop and HP laptop) Audacity recorded any sound that played on the computer. So play music or stream something, Audacity would record that if desired and the levels were okay, and manually adjustable as you would expect. That would be under Stereo Mix in. No microphone plugged in, and rarely used anyway, only for narration.
But now, on Win10 it seems Audacity will only pick up from the mic. Tried unplugging the mic and Audacity registered nothing whatsoever under any configuration of system and inputs.
This Dell has separate headphone and mic jacks to the rear, and a combo socket at the front. Only (powered) speakers are connected to the rear socket, no mic, nothing to the front socket. I can hear sounds perfectly on the speakers, but Audacity is only registering the sounds at unusably low level.
Hope that clarifies things a bit.