Unable to transform the variable to normal distribution
Based on your image, your data looks like it is uniformly distributed. You might try using more than 3 bins to look at the distribution more closely.
A few points related to your questions:

For uniformly distributed data, you won't be able to transform this data into a valid normal distribution
This distribution is fine for use in models, no need to change it.
Here is a good resource explaining assumptions about linear regression, this information also applies to many other algorithms