Toilet won't flush

Noticed that one of the tank bolts was leaking. Replaced all three with new rubber washers and bolts. Also replaced overflow tube, rubber gasket and flapper with new. Cleaned all bowl jets with a bent paperclip, unclogging them to perfection. Replaced rubber washer from tank to bowl. There are no leaks whatsoever. Now the toilet won't flush. The water just swirls and swirls but won't take anything down. If I pour a bucket of water into the bowl it flushes immediately taking everything down.
One other thing, since working on the toilet I am getting a "banging" in the pipes when the siphon valve stops. A "boo-Boom" sound. This is also happening when the cold water is shut off in the bath, kitchen, basement, or outside spigots. What have I done wrong? How can I fix it? Getting frustrated and desparate.