My acer notebook 5517 says : no bootable devise, acer notebook 5517 It says to open disk drive and insert reboot disk, can not open disk drive

First - re-seat the hard disk and reboot the computer. If the computer does not boot up then reboot and go into the BIOS configuration to see if the BIOS detects the hard drive. If it doesn't detect the hard drive then it could be faulty.
Then the hard drive needs to be replaced in the computer/laptop, Windows installed and the computer or laptop's device drivers plus your programs etc. to get a functioning computer/laptop again.

Go to the bios setup and see if there are any HDD installed. If no remove HDD from laptop then put it back, restart then go bios setup again and see if it is installed. If still not, you might need to replace your HDD with a new one.

Re-seat the harddisk and reboot the computer. If the computer does not boot up then reboot andgo into the BIOS configuration to see if the BIOS detects the hard drive. If itdoesn't detect the hard drive then it could be faulty.Then the hard drive needsto be replaced in the computer/laptop, Windows installed and the computer orlaptop's device drivers plus your programs etc. to get a functioningcomputer/laptop again.

Open the hard drive bay and ensure it is plugged in correctly. If that isn't the problem, try testing the hard drive. If it's ok, then the motherboard is gone.

The notebook cannot detect the hard disk when you turn on the notebook.
First - re-seat the harddisk and reboot the computer. If the computer does not boot up then reboot andgo into the BIOS configuration to see if the BIOS detects the hard drive. If itdoesn't detect the hard drive then it could be faulty. Next - to check if the harddrive is faulty, remove the hard drive and insert it into an USB hard drive adapter and connect it to a workingcomputer's USB port. If this computer cannot see itas an external hard drive and you cannot open the various folders and files,this confirms the hard drive is faulty. Then the hard drive needsto be replaced in the computer/laptop, Windows installed and the computer orlaptop's device drivers plus your programs etc. to get a functioningcomputer/laptop again.

its a problem with ur hard disk unplug and plug the hdd. otherwise check the hard disk with other pc or laptop

Your netbook is trying to boot from your Lan/Ethernet connection since It can find no working hard drive to boot from. This usually means that your hard drive has failed.
Also remember that your netbook will try to boot from other drive types including your SD card, USB Memory Stick and even a Magic Jack if you have one inserted in the flash memory slot or USB slot while rebooting the PC.
Many people have mistakenly assumed that their Netbook is messed up because they forget to remove all flash and memory sticks before rebooting.

You must set BIOS to boot from Removable USB Drive, first.

if the laptop has a floppy drive get a bootable win 98 disk. insert disk first then turn on comp. run w/o cr rom support. at command prompt type "fdisk MBR" hit enter remove disk and reboot. if still bad insert win XP disk and do the second repair not the first one let it run its course. if not well you will have to reimage the comp