C# Beginner Question

Question

Hi
I'm a beginner in C#. I have developed a form of database navigation(first record, next record, last record and previous record)  and functionality(add record, delete record, save and find). I have also take two comboboxes,  where 1 combobox displays the total no.of records and the next combobox is designed as...when we slect 5th record in combobox1 then combobox2 will show the records aftr 5th record. So, when we select a particular range from these two comboboxes....and whn we click on next button, it wil display records in that range. This is how actually it works.

when we dont select any range, the next button should be able to show the records. But i'm not able to do it. That requires to keep the code related to range in one test condiotion like only if the user has selected any item in the combobox, then it should execute, otherwise funtionality should be as usual.

Can anyone help me in this regard. If anyone dint understand what is my requirement, please be frank, i will send again.