My cd/dvd drive is unable to detect any cd/dvd.acer aspire 4520

Try this method it may work.
If you can boot up with the external USB hard drive on your Acer, then use a working computer and copy the Windows installation CD onto the external hard disk then connect the USB externak hard disk to the USB port on your Acer and boot up using the external hard drive.

Download and burn Ubuntu iso file from www.ubuntu.com to either a cd or a usb. Boot from your cd or usb and select the way of installing you want. You can choose between installing ubuntu along windows, erase everything and install ubuntu on entire hard disk or an opportunity called "something else" that lets you manage all hard disk partitions yourself.

You need to format your hard disk. Please note that formatting will erase all you data from the hard disk and all the software including the Operating system.

If you have your OS master CD you can insert it in the cd/dvd drive and restart the laptop. This will detect the OS CD and try to install it. In the installation process there is an option "Format your hard drive". You should select that option. Then it will format, mark the bad sectors, create a new boot sector and install the OS. You will be just fine.

Acer Aspire 4520 Notebook Technical Specifications:


Operating System Genuine Windows Vista Home Premium Processor AMD Athlon™ 64 X2 Dual-Core Processor TK-57 (512KB L2 cache, 1.9GHz) Chipset NVIDIA nForce 610M Memory 1GB (1GB installed in one of two memory slots) DDR2 667 SDRAM User upgradeable up to 4GB (one 2GB memory card in each slot)* subject to availability of 2GB cards
*If upgrading after initial purchase, one or more of the memory cards provided with the system may have to be replaced with optional larger memory cards in order to achieve the maximum capacity.
Storage 120GB* hard disk drive Integrated variable-speed Super-Multi drive (DVD+R, DVD-R, DVD-RAM):
-Read - 24X CD-ROM, 24X CD-R, 24X CD-RW, 8X DVD-ROM, 8X DVD-R, 8X DVD+R, 6X DVD-ROM DL (double-layer), 6X DVD-R DL (double-layer), 6X DVD+R DL (double-layer), 6X DVD-RW, 6X DVD+RW, 5X DVD-RAM
-Write - 24X CD-R, 10X CD-RW, 8X DVD-R, 8X DVD+R, 4X DVD-R DL (double-layer), 4X DVD+R DL (double-layer), 6X DVD-RW, 8X DVD+RW, 5X DVD-RAM
5-in-1 card reader for optional MultiMediaCard™, Secure Digital card, Memory Stick, Memory Stick PRO™ or xD-Picture Card™

Surely to load XP is a DownGrade. As this notebook is dual core, I would run Vista 64 or better still Windows 7 64.
If you wish to persist with an old system, you require SP3 for XP.That may be available from a software store but is no longer supported by Windows.
Try http://www.notebook-driver.com/laptops-information/acer-aspire-4520-notebook-technical-specifications/ for drivers that you will require to have support from Acer.

Hope that clarifies your situation.

Will the Notebook boot from the CD/DVD with a system disk installed? Have a check first, if not:
Ensure your CD/DVD tray is empty and re boot your Notebook. If you still get the problem, I suspect the driver has corrupted. Go online to the Acer web site and download an updated driver. Follow their instructions to re install it and that should be that. If you still have a problem, maybe the drive itself has failed.

Hope that helps

check that ur hard disk shown in bios setting and select ur 1st boot able drive cd/dvd rom

Enter in the BIOS and see in the boot order or the internal units if the dvd unit is still there. If it isn't then it's dead, replace it.
If it is then you didn't do a correct reinstall. Enter the bios again and make sure the dvd unit is the first in the boot order, boot from a Linux Live-CD like PCLinuxOS and from Computer Management/ Hard Disks  delete all partitions, format the entire disk to something else then format it again to NTFS or FAT. This is the only way you can be sure you are doing a clean install.

Try to use another DVD. you told you tried you old DVD from your toshiba. maybe is not compatible.. try in another.. then use your DVD in another laptop if the same from problem.check your board and DVD connection...if this under warranty bring to warranty..

if in Bios also can not detect this is hardware problem...

You will need to install chipset driver but it will be much better if you reinstall all driver for it.

Acer Aspire 4520 driver for windows xp can be downloaded here :

http://www.drivercabinet.com/driver-acer-aspire-4520-windows-xp/

puchase one vista cd/dvd and install no other option