How did the solar system get its angular momentum? Why did Earth not fall into the Sun at the start? I know that Earth is always falling towards the Sun, but due to its sideways momentum it just misses always.  But how did it all start?  To go into detail, when the gas cloud with zero angular momentum collided, our solar system was made with planets and sun having their own angular momentum which makes them rotate.  But how did the revolution start in the beginning?  Were  they placed in such a position and distance that they started attracting each other but how ? .They were having only rotation .  But a revolution started which forced them to follow a elleptical path  so how this happened in the beginning?  Did some external force act on them and revolution started?  How was  this revolution started?

i have assumed dust cloud was having zero angular momentum but it can have any value that does not affect the question i think ?
A particle's angular momentum around a point is the particle's mass times its distance from the point times its velocity around the point.  So a small velocity at a large distance can still mean a lot of angular momentum.

The bit of a Giant Molecular Cloud which collapses to form one solar system is typically on the order of a light-year across or somewhat less. It normally possesses some angular momentum -- just from random motions if nothing else.

When it collapses to form a solar system, its size drops from maybe a light-year down to maybe 10-100 AUs. A light year is about 60,000 AUs (astronomical units), so it is collapsing to about 1/1000 the size. To conserve angular momentum, the circular velocity of the matter must increase by a factor of a thousand.  And the fraction of the matter which will form the star collapses by another factor of a thousand or so.

Not only does this give you plenty of speed, but for the star to form it actually needs to shed angular momentum.

See the Wikipedia article on angular momentum for a lot of good details.