Ka can be used as possession and preposition for male. Ko can be used referring to saying something to someone. Because ka and ko are prepositions and you need to learn where you're supposed to use which one. Similarly, aapse or tumse and tumhe don't follow a given rule. You need to learn them. Aapka can mean anyone from these "You, Your & Yours". Examples: This is your pen. یہ قلم آپ کا ہے۔ Yours obediently آپ کا فرمانبردار۔ Thank you آپ کا شکریہ Aapko can mean "to you, you, Happy birthday to you آپ کو جنم دن کی مبارک باد I am missing you. میں آپ کو یاد کر رہا/رہی ہوں۔ "میں آپ سے یاد کر رہا/رہی ہوں" اس میں حرف جر (preposition) کی غلطی ہے۔ I told you, Sir. جناب میں نے آپ کو بتایا تھا۔ جناب میں نے آپ سے کہا تھا۔ Both aapko and aapse are used to deliver same meaning if used with different words. Tumse can mean "to you, from you, you" I told you, son. بیٹا میں نے تم کو بتایا تھا۔ بیٹا میں نے تم سے کہا تھا۔ There's no rule here. Contact with me to learn more about Urdu language.

aapka aapko tumse tumhein Think of apka as " your" apka khiyal or apka ghar, something that is about the other person or belong to the other person. here khiyal and ghar are sort of nouns. apko is when doing something to the other person like "apko tang kerna" or "apko jagana". apko is being followed by i think what you call verbs. Someone with a good grasp on grammer can explain better i think. Same is for tumehien is to you in a sense somewhat informal form of apko. and tumse is from you mostly. however it's different in mein tumse piar kerta/kerti hon, Sentences in one language don't really translate in similar manner into another. I hope i was helpful in someway and didn't end up confusing anyone. Moreover, i rarely check this section, so if anyone posts a question here please drop me a message too, i will be glad to answer. This is the least I could do.

I know I got late to answer but still it might help others around. "Tumse and Tumhe" are basically synonyms which means "YOU". However, their usage differ in the language. Regards, Basheer Kharoti