How Do I Retract My Resignation?

The simple answer is in writing. It should have been delivered in writing and so it needs to be retracted thus.  There are absolutely no guarantees that you will be allowed to retract your resignation, once you've tendered your resignation, the company has no obligation to keep you!

Write it very simply but include some very positive statements about why you have decided to stay.  Include things such as 'developed closer working relationships with colleagues', ' I've found new challenges within my current position' and have grown happier in my work environment.

Don't spend a lot of time on personal reasons, people don't tend to care about your personal business, only you do.

If you can speak to your boss about it, you could explain it, but expect people to treat you like you have betrayed them a little.  If you made a fuss when you said you would leave, perhaps you need to build some bridges.