My landlord changed the amount of rent I pay, and said she would put it in writing. She has failed to do so, so would that make the lease I signed null in void?

If you have a signed lease it can't be changed without both initialing it. When did you sign the kease and when does it expire?

What type of lease, is it a month to month ? Or is it for a number of months or a year ?

If you have a written lease that is not month to month, they can not just change the rent, if it is month to month, it can be changed but would require normally at least a 30 days and some places a 60 day notice

I have been living there 1 1/2 years, but six months ago she actually lowered my rent 25.00 a month and never gave me a new lease to state that. Here's the issue, my sink backed up and she charged me 20.00 to unclog it. She stated that per the lease I'm responsible,which is ridiculous, but if she changed anything on my rental agreement wouldn't the prior lease be null an void?

Again she can't change anything without your approval. She has to give you 30 days notice and has to put it in writing.

What type of lease, is it a month to month ? or is it for a number of months or a year ?

If you have a written lease that is not month to month, they can not just change the rent, if it is month to month, it can be changed but would require normally at least a 30 days and some places a 60 day notice

It is a year lease with automatic renewal for 2 years, but if anything is changed with the rental agreement shouldn't a new lease be signed?

A new lease, or an addendum to the lease, should have been signed. But a court would not rule that a reduction of rent without a new signed lease or addendum nullified the previous lease. If you're looking to get out of your lease don't try to base it on the reduction in rent because it won't work.

... Here's the issue, my sink backed up and she charged me 20.00 to unclog it. She stated that per the lease I'm responsible,which is ridiculous, but if she changed anything on my rental agreement wouldnt the prior lease be null an void?

If she wanted to change the "prior lease", she would have needed you to sign a modification document, which evidently you did not do. So your old lease is still in effect, except that she has probably waived $25 per month.

Thus, if she is claiming you agreed to a modification requiring you to pay for clogged drains, she would have to be able to point to language in the written lease to that effect. On the other hand, clogged drains typically result from misuse by the tenatnt; so she arguably can charge you for this anyway.

My understanding is that if the clogged drain is "an emergancy" that she can do it without your consent. She is making sure no future damage happened/happens. You may dispute that she didn't contact you before the fix but I feel that it is a pretty weak argument. How did she gain knowledge of the clogged drain? If you told her then you are likely putting yourself in a position for her to have the right to fix it. Again as the person above stated "clogged drains typically result from misuse by the tenatnt; so she arguably can charge you for this anyway." It is your responsiblilty to maintain the residence in good working order if it is stated in the lease. As far as your lease being breached again lowering your monthly rate would be a hard argument that the lease has been breached. She could come back then and say that it was a temporary reduction. If they are nasty then they could say that you owe them for the difference in the amount of the lower rent that it was never in the contract and there was never a signed agreement to the lower rent. I would say your best case here is just to be happy with the lower rent and pay the $20. FYI it is not that uncommon to have verbage stating that you are responsible for maintaining the property. I have a property and it states that they will maintain the yard and keep it in accordance with city code. I also have another property that states they will clear all sidewalks within 48 hours after a snowfall in accordance with city code. Also that clearing the driveway is their responsiblilty. These are common things that many people sign thinking nothing of it. Words of advice for the future make sure you read your lease and understand what you are signing. Again as stated before if you are trying to get out of a lease this most likely won't be enough in a court of law to say there was a breach.