having problem in downgrading from win 10 to win 7

[Umair_8]

i was downgrading my laptop from WINDOW 10 to WINDOW 7. when setup starts my laptop asks for partition to install window but no partition was compatible for installation because all of GPT type. Accidentally i delete my ( DISK 0 PARTITION 1 ). now my laptop gives notification
NO BOOTABLE DEVICE -- INSERT BOOT DISK AND PRESS ANY KEY
when i insert start setup but window does not install due to GPT type partitions.
Please Please help me...

 

[jackshap]

This error happens because you are trying to install to GPT-partitioned disk when booting from installation media in non-UEFI mode.
Either boot installation media in UEFI mode, or convert your fixed disk from GPT to MBR using third party tools.