How would I write "Thinking of you on your birthday" in Chinese?

Thinking of you on your birthday
[在(zai4) 生(sheng1) 日(ri4) 會(hui4) 想(xiang3) 着(zhe) 你(ni3)。]

Those answers have grammar mistakes.

Like this: #%&*@!!!!!

it is "characters," now no longer "symbols." :) ?? (romanized as "f?ng zh?ng," stated "fung jung") is "kite" in Mandarin chinese language. ?? may well be "kite" in all diverse dialects of chinese language, they're going to all in simple terms pronounce those characters in a diverse way. i'm now no longer a close-by speaker in any admire, so if i'm incorrect somebody's welcome to suitable me! :)

intellectual,
在生日會想着你。= Thinking about you at the birthday party. It could be anyone's birthday party.

Birthday is '' 生日'', thinking of you is ''想你''........
在 你 生 日 时 想 你.
zai4 ni3 sheng1 ri4 shi2 xiang3 ni3

That depends on what dialect you are trying to use.
思想對你的生日

認為你在你的生日

認為您您的生日的

it is written in traditional chinese.