ALL letters have at least one line of rotational symmetry. However - if you mean reflective symmetry, the letters F, G, J, L, P, Q, R, S, & Z do not.
H,I,O,X,
As with the Roman alphabet, which you may be familiar with it (since you are using it to read this answer), different letters have different symmetries.
H, M, N Kind of U (because the line curves at the end) If it doesn't have to be all the way vertical... A, V, W, X, Y
H
b
o x l I
Four. F, G, J, L
the letters are : E
H, I, O, X. Of course, it may depend on the font.
H, I and X. O has infinitely many and so does have 2.
letter o and x
H,I,O,X,
Seven
Vertical lines of symmetry: A, H, I, M, O, T, U, V, W, X, Y Horizontal lines of symmetry: B, C, D, E, H, I, K, O, X Other: O
Lower case "o" and "x" both have two lines of symmetry. Upper case letters with two lines of symmetry are: "O," "X," "H" and "I."
Three capital letters that have two lines of symmetry are "O", "H", and "I" since they can be reflected either horizontally or vertically and still look the same.
I x o l