David Goodwillie hopes his return to Dundee United can rekindle his love for football after a "horrible" period on the sidelines at Blackburn.

The Scotland striker made just 11 appearances last season under five managers, including Dougie Freedman during an uninspiring loan spell at Crystal Palace, and netted only one goal.

Goodwillie re-signed at Tannadice on a six-month loan deal on Tuesday less than two years after moving to the English Premier League in a deal worth at least £2million.

That move turned sour when Rovers were relegated at the end of his debut season, during which he netted four goals, and he found himself struggling to make an impact on the pitch last term as the club's controversial owners made a number of managerial changes with Steve Kean, Henning Berg and Michael Appleton sacked before Gary Bowyer took over.

Bowyer has offered encouragement to Goodwillie that he has a future at Ewood Park and the striker is looking to get back to his best after his frustration at not playing affected him off the park.

"It's been horrible because when you're not playing it's hard to stay focused and stay happy," the 24-year-old said.

"You try your best but inside you know you're not happy."

He added: "I worked hard down there and just never really got the opportunities. The change in manager has been a big factor. How can you get a manager to like you when it is changing so often?

"There is a lot of competition and maybe the boys who were in ahead of me were doing well. There is no point changing it if it wasn't broken and I just never really got a chance.

"I don't think I should have been playing every week or anything like that but I just never really got a chance."

Goodwillie has had some difficult times off the park since making the grade at Tannadice, some of them self-inflicted, but he appeared a more mature individual when talking to the media at the club's St Andrews training ground today.

"I don't know if it has made me stronger or not but it has probably made me more professional," he said of his spell at Rovers.

"It's been frustrating but it's been good as well because I have learnt a lot. I have not played as much but I have learnt a lot and come back a wee bit more mature."

Goodwillie netted 19 goals in his last full season at Tannadice and will forever have a significant place in the club's history following his goal in the 2010 Scottish Cup final win over Ross County.

And he admitted the move has already begun to rejuvenate him.

"I got a wee call and asked if I would fancy it and right away I got a little buzz and I thought I would love to get back playing regularly and enjoy football again," he said. "It was an easy decision."

Meanwhile, United manager Jackie McNamara has tied up deals for former Tottenham trainees Calum Butcher and Kudus Oyenuga.

Butcher has signed a two-year contract and Oyenuga has committed himself for three seasons.

McNamara said: "Calum is an aggressive centre-half who is also comfortable with the ball at his feet.He is at the right age for us to continue his development and he is someone who I will look to see make an impact over the course of the season.

"Kudus will excite our fans. He is quick, direct and always looking to score goals. He also has excellent body strength for a 20-year-old and I can see him having an immediate impact at the club."

Both played for Hayes & Yeading in the Conference South last season and have impressed McNamara on trial.

The manager has a number of other players on trial, including former St Mirren player Graham Carey, and is still looking for reinforcements.

"There are two areas I would like to strengthen - the centre of defence and possibly left-back, depending on how Graham Carey does," he said.

"Young Andrew Robertson has looked very good in training but he is 19 years old and ideally I would like two fighting for the position."