...you fell into a black hole?
There are misconceptions about not being able to escape a black hole once you fall in. This is true for non-rotating black holes, but there are other possibilities for rotating black holes. As long as you avoid the singularity, you could theoretically either travel to another universe (worm hole!), or come back to our own universe - except way ahead in the future. If you head straight for the singularity or go into a non-rotating black hole, however, your death will be very... interesting.
As you near the black hole, the gravity at your feet becomes stronger than the gravity at your head. You will be pulled lengthwise and squashed horizontally at the same time, soon becoming human spaghetti. Your spaghetti corpse will continue falling towards the singularity and when it reaches it, it will add on to the mass of the black hole
… two black holes came across each other?
The two black holes will orbit each other and eventually combine into a more massive black hole. During this, enormous amounts of gravitational radiation are emitted.
... the Sun turned into a black hole?
The Sun will never turn into a black hole simply because it does not have enough mass. Only stars 25 times our Sun’s mass will die and produce a black hole. Let’s pretend the Sun was replaced by a black hole. As long as the black hole has the same mass as our Sun, we will continue our orbit as if nothing happened. Just because there is a black hole there does not mean we will be “sucked in”. Black holes don’t gobble everything around them – if that were the case our universe would just be one giant black hole by now. As long as something remains at a safe distance, the gravity cannot affect it.