(urgent help)How to recover my 250gb hard disk?

I have done a terrible thing..,i used minitool partition manager to merge my 250gb partition and 15gb partition and cancelled it when the process is going on...now my 250gb partition in 500gb hard disk is only showing the icon...when i click it,it shows disk not formatted continue to format...please help to recover my partition..i have nearly 300 full movies in it...i would be grateful