Undergraduate transcript for graduate addmission
You're not going to like this, but the answer is, "it depends."

If you flunked computer science, it'll be hard to find a CS program that will take you.  If you flunked underwater basket weaving and want admission to a CS program, well, that might work.  If "failed one subject" means "failed one course," that might not be too bad.  If it means "never passed even one history course, " not so much.

It also depends on how long it's been since you were an undergraduate.  Admissions committees understand that people mature and that a poor showing in the distant past doesn't necessarily mean you'll be a poor scholar today.

To be blunt, it also depends on the school to which you apply.  Harvard probably won't take you, but there could be schools that might.  Pick a couple, visit them in person with a copy of your transcript, and ask.  You'll need an appointment for that personal visit; if you just show up, no telling who will talk to you.  You're visiting in person to show them you're serious.