Which sentence is correct,
"She told me she will buy it" or
" She told me she would buy it"

Question

Which sentence is correct, 
"She told me she will buy it" or 
" She told me she would buy it"

Answer

It depends on the context. Either can be right.

Do a Google search for “verb changes for reported speech” or consult a grammar book such as English Grammar in Use by Raymond Murphy.

Answer

It depends when the buying happens.

Answer

" She told me she would buy it"