several reasons pick the appropriate ones
didnt grease pan
coated pan with scratches(where the teflon is gone the cake will stick)
cooled in pan too long
de-panned before cool enough
batter not thoroughly mixed
pound cake always sounds simple , but this a unique cake to get right . Your ingredients must be totally mixed and you have a window to get that cake out of the pan. My sister always puts her cooled cake and pan into the freezer and then dips the frozen bottom into warm water to loosen the cake . She swears that a partially frozen cake isnt as easy to break.
I have an Anolon cookware. Its a bit more expensive but it is excellent ! Also for a cheaper idea would be the silicone bakeware. Spray them well and they come out pretty easily.
Use Crisco (the white shortening kind) or Crisco Pan Release, or Baker's Joy to spray the pan. Or use Pam.
Make sure you get the shortening into all the nooks and crannies of the bundt pan. Sprinkle lightly with flour, tap the flour around for side to side and turn the pan upside-down to shake out any excess.
When the cake is done, free the edges of the cake with a butter knife all around the pan before making any attempts to remove it. After it's out of the oven a few minutes and it's begun to set, it sometimes helps with a stubborn recipe, to balance the center of the bundt (or angel food) pan on a support, such as a bottle so that the cake hangs freely upside down. This allows it to cool while pulling away from the pan.
Hope this helps!
I always grease my entire pan with crisco and then put about 2-3 tablespoons of flour in it and shake it around over all the entire surface of the pan--anywhere the batter might touch. Then shake out any excess flour into the trashcan. When your cake comes out the oven let it sit for 5-10 minutes to cool, then run a knife around the edges if it looks like it is sticking. Put a plate on top and flip over gently. It should come out nicely.
I grease the pan and line the bottom of the pan with baking parchment so you only have the sides of the pan to loosen slightly with a small knife.