Where can i find a manual for an ASTRA car alarm system

There is no separate alarm owners manual for the factory fit alarm. If your car has had an aftermarket alarm fitted by a previous owner suggest you find out which manufacturer it came from and check their website for a downloadable file.

you will need to get a new remote most astra alarms 2 ways controls can be progam

Needs to be reprogrammed, system lost the match codes that go with the handheld. Two days was two days to long without power, system and the key fobs are not matched up.

Your Astra must have a backup battery, have to find the unit and disconnect the backup battery to stop siren

I would google the Astra system - include the model number. I did a simple google and came up with
http://www.commandocaralarms.com/manuals/a4000RSmanual.pdf

but I have no idea if this is your system or not.

STOP STOP STOP STOP STOP STOP OK OK OK OK OK OK OK OK OK OK OK OK

The batteries take a lot of power to send and receive data so you should get around 3 to 4 weeks per battery. If this is what you get it is normal.

Hi there's this website something
like reliable-store and it is very amazing for manual for repairing servicing anything
someone on fixya recommended it to me and I thank him even today
They have full manuals free

Manual link found at the top right of the page: http://www.scytek.net/astra.php?pic=images/products/astra/a1000RS.png

Hope this helps.
http://scytek.net/manuals/astra/a600.pdf