Can anyone please shed a bit of light on the use of seni and sen. Thank youuuuuuuuu

Sen means you.

Sen de gel (You come too, you come also)

Seni means you, and indicates a verb is coming that affects or relates to you.

Seni seviyorum. (I love you.)

Sana also means you, but tells us something is coming to or for you.

Sana çiçekleri getirdim (I brought flowers for you.) 

Senden means from you

Senden mesajý aldým. (I received the message from you) 

A similar thing occurs for ben (I), beni, bana, benden.

I´m not a grammer expert let me give it a try:

Seni => (you as object)

I love you - Seni seviyorum

We don´t want you - Seni istemiyoruz.

Sen=> (you as subject)

You are an idiot - Sen bir aptalsýn

You weren´t there - Sen orada deðildin.

If you put it like this difference is obvious.

When you is object of the verb it becomes ´seni´ whereas it is subject of  the sentence it becomes ´sen´.

In Turkish every noun can be written in one of five states.   These states are made by adding a suffix to the end of the noun.   On their own they generally indicate direction but they are also applied according to the verb in use and for the most part you need to learn which verb takes which form.

Example:

ev - house (any house)

evi - the house (a particular house)

eve - towards (or to) the house

evde - at/in the house

evden - away from the house

You/me (sen/ben) are slightly irregular and are:

sen

seni

sana

sende

senden

Different verbs take different states such as:

 - istemek (to want) takes no state

 - sevmek (to love) takes the ý state

 - bakmak (to look at) takes the e state

 - konuþmak (to talk) takes the de state

 - hoþlanmak (to like) takes the den state

Therefore:

 - sen istiyorum - I want you

 - seni seviyorum - I love you

 - sana baðýyorum - I am looking at you

 - sende konuþýyorum - I am talking with you

 - senden hoþlanýyorum - I like you

A few verbs have a different meaning depending on the noun state - for example bulmak is ´to find´ when used with the ý suffix but ´to accuse´ when used with the e suffix

Nice Explanation however needs some corrections as follows:

- evden - away from the house

- seni istiyorum - I want you

- sana bakðýyorum - I am looking at you

- sende konuþýyorum - I am talking with you - seninle konuþuyorum