On this site I provide free downloads of the One-Hand Keyboard typing software.
Give the free one-handed typing apps for Mac and Windows PC a try. They will allow you to type with one hand very easily, provided that you used to be a two-handed touch typist.
Anyone who used to type on the home row with two hands will be able to learn to type with one hand in minutes.
Give the demo apps a try. See if one-handed typing works for you. There is no obligation to buy.
The Mac demo is available on the Mac App Store.
If you do find these free trial apps useful, please post two things as a comment below.
1. Why are you typing with one hand? Injury? Medical condition?
2. How is demo working for you?