@Vinayak2, thanks for reaching out to is on HP Support Forums. I'm glad to assist you with your HP Notebook - 15-ac072tx. I understand that when you attempted a minimized image recovery and it resulted in an error CTOERROR.FLG. I suggest you to first run the hard drive test on the laptop. Please follow this link to run hard drive test: http://hp.care/2bOrqZQ.
If the hard drive test passes the please attempt the below steps before initiating a system recovery:
Go to BIOS by hitting the F10 key on startup.
In BIOS, change the system date to the year 2012.
Hit F10 key to save the changes and exit.
Reattempt the system recovery by booting to recovery partition by hitting the F11 key on startup or y using the USB flash drive. Let me know the outcome. Cheers! 🙂