[bitlover]

I tried to re-size the HDD of my new Dell inspiron 7520 laptop and now I can not recover my old OS or even install a new one since during my new installation there is no HDD is visible.

I took an image using acronis software on a flash disk but I still can get it working

[Appzalien]

A hard drive needs to be initialized before it will be recognized for an installation. If it were a secondary drive you could see it and initialize it from within Windows, but since it's the only drive, you will have to use a boot utility to initialize the drive. You would also need an Acronis boot disk to be able to see the backup on the flash drive. Try searching for a free boot disk like UBCD or similar. I hope your laptop has an optical drive. They're starting to go the way of the floppy.

[farvaknowsbest]

Almost sounds like your MBR got hosed. If you have the Windows Disc, try booting to that, and then choosing repair Windows after it loads. Bring up a command prompt and type the following commands in order:

Bootrec.exe /fixmbr
Bootrec.exe /fixboot
Bootrec.exe /rebuildbcd

If you do not get any error messages when doing this, reboot the PC to the HDD and see if it works. Hope that helps.