Question

Lying in bed, swami realized that it was Monday morning.(change into complex sentence)

Answer 1

hii mate here is the answer to your question: -
when swami was lying in his bed he realosed that it was monday morning.
hope this helps you
keep smiling

Answer 2

The complex sentence refers to the sentence which contains at least one dependent clause and an independent clause. A dependent clause is the clause which cannot stand alone in its meaning on the other hand independent clause refers to the phrase which can stand alone, though both have a subject and a verb.  

Therefore, when the above sentence converted into complex sentence can be written as:

While Swami was lying on bed he realized that it was Monday morning.