Try to do = attempt to do, make an effort to do:
• I was very tired. I tried to keep my eyes open but I couldn't.
• Please try to be quiet when you come home. Everyone will be asleep.
Try also means 'do something as an experiment or test'. For example:
• These cakes are delicious. You must try one. (= you must have one to see if you like it)
• We couldn't find anywhere to stay. We tried every hotel in the town but they were all full. (= we went to every hotel to see if they had a room)
If try (with this meaning) is followed by a verb, we say try -ing:
• A: The photocopier doesn't seem to be working.
B: Try pressing the green button. (= press the green button - perhaps this will help to solve the problem)
Compare:
• I tried to move the table but it was too heavy, (so I couldn't move it)
• I didn't like the way the furniture was arranged, so I tried moving the table to the other side of the room. But it still didn't look right, so I moved it back again.
Need to... and need -ing
• I need to take more exercise.
• He needs to work harder if he wants to make progress.
• I don't need to come to the meeting, do I?
Something needs doing = something needs to be done:
• The batteries in the radio need changing. (= they need to be changed)
• Do you think my jacket needs cleaning? (=needs to be cleaned)
• It's a difficult problem. It needs thinking about very carefully. (= it needs to be thought about)