i have install windows 7 without creating back up of original installed windows 8

[thal]

and i do not have any recovering disk also. Now how to recover it. On lenovo n580

 

[Joey2oo9]

You didn't want windows 8, so why the concern about it now? Just backup up your windows 7 install and use it for recovery purposes.

 

[das_stig]

Chapter 4 - One Key Rescue

http://download.lenovo.com/consumer/mobiles_pub/ideapad_p580_p585_n580_n581_n585_n586_ug_v1.0_english.pdf

This may be of use.

http://support.lenovo.com/en_GB/research/hints-or-tips/detail.page?DocID=HT073636

 

[hang-the-9]

If you wiped the restore partition, you need to contact Lenovo for a recovery disk set.