My 20 month old son, like any other baby is always wanting to grab something and when we don't let he starts crying and runs to a corner of the house and just sits crying.
Having a toddler, I deal with this a lot. My responses are usually some combination of the following:
1. Oops, that's not for touching. (before he grabs the item--sometimes effective)
2. Confiscate/redirect. Can I see that? Here's something for you...(often works)
3. Oops, that's dangerous, ouchy, hot, etc. Not safe! Sorry bud. Here's lets go do something else...
4. Environmental modification (knowing what some of his triggers are, I try to make sure he doesn't have access to the things I'm most concerned about--or has adequate alternatives to those items (e.g. nonworking remotes).
5. Brief exploration--sometimes if it's not dangerous, I'll let him explore the item for a minute, but then it goes bye-bye.
6. That's life--sometimes I have to take something away, and there's nothing much that can be done about it. I try to be empathetic but firm (I know you want that, but it's going bye-bye now), he cries, I dry his tears, and we regroup and move on with our lives.
My kid isn't particularly strong willed, so as long as I catch him early, I can usually get him to surrender the object without a lot of fuss. I realize gentle approaches often don't work well with stronger-willed children.