You may be able to make some improvements but the sad truth is, most recording defects can’t be fixed. Most professional recordings are recorded in perfectly-controlled conditions in a soundproof studio. Most professional “live” recordings are close-mic’d, multi-tracked, and mixed in the studio. (And they usually record multiple performances and choose the best parts of each to re-assemble a “live” performance.)
that sound like overdue or that the files have been over-edited.
Again, most “processing” such as compression, reverb, or mixing can’t be reversed. EQ can sometimes be reversed.
As if some sound sounded like that, some stereo sound would be as mono sounding
Most live sound is mostly-mono (or “narrow”). PA systems are almost always mono so people sitting to the left, right, and center hear the same mix.
If you’re listening to an orchestra or choir in a concert hall it’s hard to tell what sounds are coming from the left or right (with your eyes closed) and there is a lot of sound reflecting/reverberating from all directions so you don’t hear a “simple stereo image”. When they record that kind of sound the (directional) microphones are close to the stage to “enhance” the stereo effect.
With close-mic’d and multitracked “live” rock music the sounds are panned left to right during mixing to create a stereo image, just like a studio recording.
There are ways to make “fake stereo” or “simulated stereo” from mono but many people don’t like the effect and it often sounds bad when played-back on a mono system (worse than the original mono).
A true-mono recording will play through both speakers. If you’re only getting one side or if the left & right are out-of-balance, that’s a different issue and that can be corrected even if you have to make a true-mono file.
the sound would be completely missing some quality track that would create more space for the sound so, is there any way to fix such files so that they sound more softer and more vivid?
Sorry, I don’t know what that means… “Softer” may mean turning-down the volume or reducing the high frequencies with EQ. (That’s easily done.)
The 1st thing is to try to diagnose the problems… Diagnosis before treatment.
There are essentially 5 things that effect/define “audio quality” (ignoring performance or mixing issues)
1. Noise - Unwanted sound like an amplifier buzzing or hissing, or excessive audience noise (or audience noise at inappropriate times) or a barking dog, etc. Noise on a live recording is virtually impossible to remove if it’s happening at the same time as the music. (Low-level noise in studio recordings can sometimes be fixed with noise reduction). Noise on a recording is usually more annoying than the original-live noise. Sometimes you might not be aware of the noise 'till you listen to the recording.
2. Distortion - Distortion is usually caused by “overloading” electronics. If crank-up a 100 Watt amplifier and try to get 200W out of it, that’s distortion (clipping). You can also distort clip your analog-to-digital converter if you record too “hot”. Generally, distortion can’t be fixed.
3. Frequency response - Excess bass, excessive highs, or slightly-weak highs or lows can be improved tweaked with EQ (equalization).
4. Excessive acoustic reverb or echo - These cannot be fixed. The natural reverb that sounds great live in a music hall usually sounds unnatural when reproduced in a living room.
5. Speed/timing errors - Speed & timing errors are rare but if the speed (and pitch) is slightly-off it can be corrected as long as it’s constant.