When you say 'unable to complete', do you mean that you dropped out due to bad grades, or that you had problems, but you left with a decent GPA?
If you have a decent GPA, it shouldn't be too hard to get back into the same school (or a different one); if your grades were bad, you'll probably have to show them that you can do better than the last time.
Some schools have an online application process, and all of them should have a website that talks about what is involved in applying.
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"A dead thing can go with the stream, but only a living thing can go against it." --G. K. Chesterton