Recovering Windows 7 after installing windows 8.1 manually.

Hi,

I have a dell inspiron laptop. It had windows 7 installed when I bought it.

Recently I installed windows 8.1 manually using ISO image. Now my system is consuming lot of power and hence battery backup is very low. Laptop get heated soon. So I need to go back to the windows 7 which I had when I bought the laptop ( Factory settings). But I could not find the recovery windows 7. i.e when I check for recovery image in command prompt 

C:\> recimg /showcurrent

Error message is : Thers is no active custom recovery image. Error code - 0x80070490 

How I can get back my laptop to factory settings.

I contacted dell customer care but since my warranty is over they are not giving solutions.

Anyone  please help me regarding this.

Thank you,