I myself does not know this.
I myself don't know this.
Which sentence is correct grammatically?
And also why?
I myself does not know this. incorrect I myself don't know this. correct The uncontracted form of #2 above is I myself do not know this.
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I myself does not know this. incorrect
I myself don't know this. correct
The uncontracted form of #2 above is I myself do not know this.
And also why? The subject is considered to be in the first person singular.
Note that in the third person singular, we'd say
He himself does not know this.
Clive