DVD player won't work!

Hmmmm.
I've seen this before with a CD player that kept shutting down when you pressed one of the remote keys.
Turned out that the remote had gone bananas and was transmitting the shutdown code regardless of what was pressed and at random intervals !
Try taking the batteries out of the remote and just using the front panel controls.
If it doesn't work then there's something inside there that's toast.
I can only suggest you take it to a repair shop and see what they have to say.
They're not hard to fix.

One thing you might try is a "Hard Reset" of the unit; switch it off, then unplug it and leave it unplugged an hour or so. Plug it back in, use its front-panel controls, and see what happens.

Might not be practical, from a repair cost-vs-replacement cost to actually effect a repair of any real magnitude. Sad-but-true, almost nothing in a device like a consumer AV product actually is "repairable" - modules and assemblies are swapped out and replaced as opposed to anything actually bein' "fixed" in the traditional sense. Parts cost alone, not even considerin' labor, often approaches or exceeds the cost of replacin' the device with somethin' new offerin' similar, same, or superior performance and features. Naturally, thats less applicable to higher-end, serious audiophile-type gear. Aiwa, however, really has no product in that market segment.

All true.
I fixed a mate's CD player in about 5 minutes when I realised that the mechanism was identical to the one in a Playstation 1 !! Same connectors, everything.
Had an old PS1 that was toast so I swapped it out and my friend went away a happy girl.

DVD player is very cheap in malaysia now, a non-branded one is just about 30USD, to buy a good one like Sony/JVC. it is about USD$90