Why does my iPhone autocorrect into misspelled words?

For example, tgere is not a word, but won't correct to the proper spelling "there".

Check your settings in the keyboard section and check auto correct is switched on:-)

You've spelled something so wrong so many times it now remembers it. It learns from it's user over time and will store your slang-right or wrong. Best luck.

If you spelt it wrong enough times it takes it in its database.