HTC desire 501

[hero121]

Dear All,
Please help
My htc desire 501 is just two month old I have got unlocked boot loader through Welcome to HTCdev
After rooted with v root.exe
I had installed titanium backup working well. but one day due to my fault working with titanum backup it hangup and I did factory reset. after that The phone got unrooted, now it is not unrooting or rooting with any way. there is no any cwm recovery available for this set. the problem is :
The SU Binary file is corrupted on my device, used SuperUser.apk. I reset my phone, hoping this would unroot my device. I was WRONG. My device is now currently rooted, with a corrupted SU file, so i can't even unroot via SuperSU Application. I've also tried terminal commands to remove the SU file, but it needs root access, which i cannot access due to the SU file! HOW CAN I UNROOT MY PHONE , THUS GETTING RID OF /SYSTEM/BIN/SU , SO I CAN SUCCESSFULLY RE-ROOT MY PHONE?

I HAVE ALREADY TRIED RE-ROOTING / UNROOTING, BUT NO LUCK, STILL ROOTED BUT ACTING UNROOTED!

PLEASE LEAVE A SUGGESTION, OR LINK ME TO SOME UNROOTING SOFTWARE, I'M IN DESPERATE NEED OF HELP