In the Name of Allah, the Inspirer of Truth.
Assalamu Alaikum Warahmatullahi Wabarakatuh

1. Ghusl is valid. Just think of something else, rather than fighting evil thoughts.
2. Salaah is valid. Try your best to keep concentration on what you are doing at the time. That is to say, if you are reading Qir'aat, then concentrate on what you are reading. Make sure your hands, fingers are in the right place in ruku', Qawmah, Sajdah etc. By building concentration on the physical aspect of your Salaah, you will gain concentration and devotion all round Insha-Allah Ta'ala.

We are not responsible for
involuntary thoughts which enter the mind during acts
of worship nor do they affect their validity.

Therefore, there is nothing to worry about. You should
continue with your wudhu, ghusl and Salaat and perform
them according to the Sunnah of our beloved Rasulullah
(sallallahu alaihi wa sallam). Insha-Allah, through
the blessings of following the Sunnah, your thoughts
will disappear.

To dispel your thoughts you may also recite,

1) Ta'awwuz - i.e. Auzoo Billah ....

2) A'amantu Billahi Wa Rusulihi

And Allah knows Best
Wa Alaykumussalaam Wa Rahmatullahi Wa Barakatuh
www.foodguide.org.uk